From 7a36e5837e0242a27b8f8b27b2ed46617678d62b Mon Sep 17 00:00:00 2001 From: Scott B Date: Sun, 14 Nov 2021 04:20:28 -0800 Subject: [PATCH] squashed mm multigenerational lru v5 for 5.15.y Squashed commit of the following: commit 19e8961fca725ce8ee2643cb2ff4a818c864ee30 Author: Yu Zhao Date: Wed Nov 10 21:15:10 2021 -0700 mm: multigenerational lru: documentation Add Documentation/vm/multigen_lru.rst. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit 4326538c0c4edf38c30156b2ff956bc7df448249 Author: Yu Zhao Date: Wed Nov 10 21:15:09 2021 -0700 mm: multigenerational lru: Kconfig Add configuration options for the multigenerational lru. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit 1fbf643cde24bf5b7925a6dc2b6f04832519213a Author: Yu Zhao Date: Wed Nov 10 21:15:08 2021 -0700 mm: multigenerational lru: user interface Add /sys/kernel/mm/lru_gen/enabled to enable and disable the multigenerational lru at runtime. Add /sys/kernel/mm/lru_gen/min_ttl_ms to protect the working set of a given number of milliseconds. The OOM killer is invoked if this working set cannot be kept in memory. Add /sys/kernel/debug/lru_gen to monitor the multigenerational lru and invoke the aging and the eviction. This file has the following output: memcg memcg_id memcg_path node node_id min_gen birth_time anon_size file_size ... max_gen birth_time anon_size file_size min_gen is the oldest generation number and max_gen is the youngest generation number. birth_time is in milliseconds. anon_size and file_size are in pages. This file takes the following input: + memcg_id node_id max_gen [swappiness] [use_bloom_filter] - memcg_id node_id min_gen [swappiness] [nr_to_reclaim] The first command line invokes the aging, which scans PTEs for accessed pages and then creates the next generation max_gen+1. A swap file and a non-zero swappiness, which overrides vm.swappiness, are required to scan PTEs mapping anon pages. The second command line invokes the eviction, which evicts generations less than or equal to min_gen. min_gen should be less than max_gen-1 as max_gen and max_gen-1 are not fully aged and therefore cannot be evicted. Setting nr_to_reclaim to N limits the number of pages to evict. Setting use_bloom_filter to 0 overrides the default behavior which only scans PTE tables found populated. Multiple command lines are supported, as is concatenation with delimiters "," and ";". Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit 273f053f193dcca266045fabef04e6083e65e7a7 Author: Yu Zhao Date: Wed Nov 10 21:15:07 2021 -0700 mm: multigenerational lru: eviction The eviction consumes old generations. Given an lruvec, the eviction scans pages on lrugen->lists indexed by anon and file min_seq[] (modulo MAX_NR_GENS). It first tries to select a type based on the values of min_seq[]. If they are equal, it selects the type that has a lower refaulted %. The eviction sorts a page according to its updated generation number if the aging has found this page accessed. It also moves a page to the next generation if this page is from an upper tier that has a higher refaulted % than the base tier. The eviction increments min_seq[] of a selected type when it finds lrugen->lists indexed by min_seq[] of this selected type are empty. Each generation is divided into multiple tiers. Tiers represent different ranges of numbers of accesses from file descriptors only. Pages accessed N times via file descriptors belong to tier order_base_2(N). Each generation contains at most MAX_NR_TIERS tiers, and they require additional MAX_NR_TIERS-2 bits in page->flags. In contrast to moving between generations which requires list operations, moving between tiers only involves operations on page->flags and therefore has a negligible cost. A feedback loop modeled after the PID controller monitors refaulted % across all tiers and decides when to protect pages from which tiers. Unmapped pages are initially added to the oldest generation and then conditionally protected by tiers. Each tier keeps track of how many pages from it have refaulted. Tier 0 is the base tier and pages from it are evicted unconditionally because there are no better candidates. Pages from an upper tier are either evicted or moved to the next generation, depending on whether this upper tier has a higher refaulted % than the base tier. This model has the following advantages: 1) It removes the cost in the buffered access path and reduces the overall cost of protection because pages are conditionally protected in the reclaim path. 2) It takes mapped pages into account and avoids overprotecting pages accessed multiple times via file descriptors. 3 Additional tiers improve the protection of pages accessed more than twice. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit b8ff3328e2852e88df92042311f4169d231b8628 Author: Yu Zhao Date: Wed Nov 10 21:15:06 2021 -0700 mm: multigenerational lru: aging The aging produces young generations. Given an lruvec, the aging traverses lruvec_memcg()->mm_list and calls walk_page_range() to scan PTEs for accessed pages. Upon finding one, the aging updates its generation number to max_seq (modulo MAX_NR_GENS). After each round of traversal, the aging increments max_seq. The aging is due when min_seq[] reaches max_seq-1. The aging uses the following optimizations when walking page tables: 1) It skips non-leaf PMD entries that have the accessed bit cleared when CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=y. 2) It does not zigzag between a PGD table and the same PMD or PTE table spanning multiple VMAs. In other words, it finishes all the VMAs within the range of the same PMD or PTE table before it returns to this PGD table. This optimizes workloads that have large numbers of tiny VMAs, especially when CONFIG_PGTABLE_LEVELS=5. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit 18f292b52b7de4353ea1083a9f985fa69381ada8 Author: Yu Zhao Date: Wed Nov 10 21:15:05 2021 -0700 mm: multigenerational lru: mm_struct list To scan PTEs for accessed pages, a mm_struct list is maintained for each memcg. When multiple threads traverse the same memcg->mm_list, each of them gets a unique mm_struct and therefore they can run walk_page_range() concurrently to reach page tables of all processes of this memcg. This infrastructure also provides the following optimizations: 1) it allows walkers to skip processes that have been sleeping since the last walk by tracking the usage of mm_struct between context switches. 2) it allows walkers to add interesting items they find during a walk to a Bloom filter so that they can skip uninteresting items during the next walk by testing whether an item is in this Bloom filter. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit 089e38620dad513b66f01490392cb9dd40667853 Author: Yu Zhao Date: Wed Nov 10 21:15:04 2021 -0700 mm: multigenerational lru: groundwork For each lruvec, evictable pages are divided into multiple generations. The youngest generation number is stored in lrugen->max_seq for both anon and file types as they are aged on an equal footing. The oldest generation numbers are stored in lrugen->min_seq[] separately for anon and file types as clean file pages can be evicted regardless of swap constraints. These three variables are monotonically increasing. Generation numbers are truncated into order_base_2(MAX_NR_GENS+1) bits in order to fit into page->flags. The sliding window technique is used to prevent truncated generation numbers from overlapping. Each truncated generation number is an index to lrugen->lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]. The framework comprises two conceptually independent components: the aging, which produces young generations, and the eviction, which consumes old generations. Both can be invoked independently from user space for the purpose of working set estimation and proactive reclaim. The protection of hot pages and the selection of cold pages are based on page access types and patterns. There are two access types: one via page tables and the other via file descriptors. The protection of the former type is by design stronger because: 1) The uncertainty in determining the access patterns of the former type is higher due to the coalesced nature of the accessed bit. 2) The cost of evicting the former type is higher due to the TLB flushes required and the likelihood of involving I/O. 3) The penalty of under-protecting the former type is higher because applications usually do not prepare themselves for major faults like they do for blocked I/O. For example, client applications commonly dedicate blocked I/O to separate threads to avoid UI janks that negatively affect user experience. There are also two access patterns: one with temporal locality and the other without. The latter pattern, e.g., random and sequential, needs to be explicitly excluded to avoid weakening the protection of the former pattern. Generally the former type follows the former pattern unless MADV_SEQUENTIAL is specified and the latter type follows the latter pattern unless outlying refaults have been observed. Upon faulting, a page is added to the youngest generation, which provides the strongest protection as the eviction will not consider this page before the aging has scanned it at least twice. The first scan clears the accessed bit set during the initial fault. And the second scan makes sure this page has not been used since the first scan. A page from any other generations is brought back to the youngest generation whenever the aging finds the accessed bit set on any of the PTEs mapping this page. Unmapped pages are initially added to the oldest generation and then conditionally protected by tiers. This is done later [PATCH 07/10]. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit ece1399ffe2c76ce020e7041c4790f1ace13f77c Author: Yu Zhao Date: Wed Nov 10 21:15:03 2021 -0700 mm/vmscan.c: refactor shrink_node() This patch refactors shrink_node(). This will make the upcoming changes to mm/vmscan.c more readable. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit 103c3bb04169ccac581e524ca267961377e474fb Author: Yu Zhao Date: Wed Nov 10 21:15:02 2021 -0700 mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Some architectures support the accessed bit on non-leaf PMD entries, e.g., x86_64 sets the accessed bit on a non-leaf PMD entry when using it as part of linear address translation [1]. As an optimization, page table walkers who are interested in the accessed bit can skip the PTEs under a non-leaf PMD entry if the accessed bit is cleared on this PMD entry. Although an inline function may be preferable, this capability is added as a configuration option to look consistent when used with the existing macros. [1]: Intel 64 and IA-32 Architectures Software Developer's Manual Volume 3 (June 2021), section 4.8 Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov commit fa446f371f7398741969012da6364558fe209d9a Author: Yu Zhao Date: Wed Nov 10 21:15:01 2021 -0700 mm: x86, arm64: add arch_has_hw_pte_young() Some architectures automatically set the accessed bit in PTEs, e.g., x86 and arm64 v8.2. On architectures that do not have this capability, clearing the accessed bit in a PTE triggers a page fault following the TLB miss of this PTE. Being aware of this capability can help make better decisions, i.e., whether to limit the size of each batch of PTEs and the burst of batches when clearing the accessed bit. Signed-off-by: Yu Zhao Tested-by: Konstantin Kharlamov --- Documentation/vm/index.rst | 1 + Documentation/vm/multigen_lru.rst | 132 ++ arch/Kconfig | 9 + arch/arm64/include/asm/cpufeature.h | 5 + arch/arm64/include/asm/pgtable.h | 13 +- arch/arm64/kernel/cpufeature.c | 10 + arch/arm64/tools/cpucaps | 1 + arch/x86/Kconfig | 1 + arch/x86/include/asm/pgtable.h | 9 +- arch/x86/mm/pgtable.c | 5 +- fs/exec.c | 2 + fs/fuse/dev.c | 3 +- include/linux/cgroup.h | 15 +- include/linux/memcontrol.h | 7 + include/linux/mm.h | 36 + include/linux/mm_inline.h | 198 ++ include/linux/mm_types.h | 106 ++ include/linux/mmzone.h | 175 ++ include/linux/nodemask.h | 1 + include/linux/oom.h | 16 + include/linux/page-flags-layout.h | 19 +- include/linux/page-flags.h | 4 +- include/linux/pgtable.h | 17 +- include/linux/sched.h | 3 + include/linux/swap.h | 3 + kernel/bounds.c | 3 + kernel/cgroup/cgroup-internal.h | 1 - kernel/exit.c | 1 + kernel/fork.c | 10 + kernel/kthread.c | 1 + kernel/sched/core.c | 2 + mm/Kconfig | 59 + mm/huge_memory.c | 3 +- mm/memcontrol.c | 31 + mm/memory.c | 21 +- mm/mm_init.c | 6 +- mm/oom_kill.c | 4 +- mm/page_alloc.c | 1 + mm/rmap.c | 8 + mm/swap.c | 51 +- mm/swapfile.c | 2 + mm/vmscan.c | 2697 ++++++++++++++++++++++++++- mm/workingset.c | 120 +- 43 files changed, 3679 insertions(+), 133 deletions(-) create mode 100644 Documentation/vm/multigen_lru.rst diff --git a/Documentation/vm/index.rst b/Documentation/vm/index.rst index b51f0d8992f8..779772a025a0 100644 --- a/Documentation/vm/index.rst +++ b/Documentation/vm/index.rst @@ -17,6 +17,7 @@ various features of the Linux memory management swap_numa zswap + multigen_lru Kernel developers MM documentation ================================== diff --git a/Documentation/vm/multigen_lru.rst b/Documentation/vm/multigen_lru.rst new file mode 100644 index 000000000000..7c064a378b85 --- /dev/null +++ b/Documentation/vm/multigen_lru.rst @@ -0,0 +1,132 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================== +Multigenerational LRU +===================== + +Quick Start +=========== +Build Configurations +-------------------- +:Required: Set ``CONFIG_LRU_GEN=y``. + +:Optional: Set ``CONFIG_LRU_GEN_ENABLED=y`` to turn the feature on by + default. + +Runtime Configurations +---------------------- +:Required: Write ``1`` to ``/sys/kernel/mm/lru_gen/enable`` if the + feature was not turned on by default. + +:Optional: Write ``N`` to ``/sys/kernel/mm/lru_gen/min_ttl_ms`` to + protect the working set of ``N`` milliseconds. The OOM killer is + invoked if this working set cannot be kept in memory. + +:Optional: Read ``/sys/kernel/debug/lru_gen`` to confirm the feature + is turned on. This file has the following output: + +:: + + memcg memcg_id memcg_path + node node_id + min_gen birth_time anon_size file_size + ... + max_gen birth_time anon_size file_size + +``min_gen`` is the oldest generation number and ``max_gen`` is the +youngest generation number. ``birth_time`` is in milliseconds. +``anon_size`` and ``file_size`` are in pages. + +Phones/Laptops/Workstations +--------------------------- +No additional configurations required. + +Servers/Data Centers +-------------------- +:To support more generations: Change ``CONFIG_NR_LRU_GENS`` to a + larger number. + +:To support more tiers: Change ``CONFIG_TIERS_PER_GEN`` to a larger + number. + +:To support full stats: Set ``CONFIG_LRU_GEN_STATS=y``. + +:Working set estimation: Write ``+ memcg_id node_id max_gen + [swappiness] [use_bloom_filter]`` to ``/sys/kernel/debug/lru_gen`` to + invoke the aging, which scans PTEs for accessed pages and then + creates the next generation ``max_gen+1``. A swap file and a non-zero + ``swappiness``, which overrides ``vm.swappiness``, are required to + scan PTEs mapping anon pages. Set ``use_bloom_filter`` to 0 to + override the default behavior which only scans PTE tables found + populated. + +:Proactive reclaim: Write ``- memcg_id node_id min_gen [swappiness] + [nr_to_reclaim]`` to ``/sys/kernel/debug/lru_gen`` to invoke the + eviction, which evicts generations less than or equal to ``min_gen``. + ``min_gen`` should be less than ``max_gen-1`` as ``max_gen`` and + ``max_gen-1`` are not fully aged and therefore cannot be evicted. + Use ``nr_to_reclaim`` to limit the number of pages to evict. Multiple + command lines are supported, so does concatenation with delimiters + ``,`` and ``;``. + +Framework +========= +For each ``lruvec``, evictable pages are divided into multiple +generations. The youngest generation number is stored in +``lrugen->max_seq`` for both anon and file types as they are aged on +an equal footing. The oldest generation numbers are stored in +``lrugen->min_seq[]`` separately for anon and file types as clean +file pages can be evicted regardless of swap and writeback +constraints. These three variables are monotonically increasing. +Generation numbers are truncated into +``order_base_2(CONFIG_NR_LRU_GENS+1)`` bits in order to fit into +``page->flags``. The sliding window technique is used to prevent +truncated generation numbers from overlapping. Each truncated +generation number is an index to an array of per-type and per-zone +lists ``lrugen->lists``. + +Each generation is divided into multiple tiers. Tiers represent +different ranges of numbers of accesses from file descriptors only. +Pages accessed ``N`` times via file descriptors belong to tier +``order_base_2(N)``. Each generation contains at most +``CONFIG_TIERS_PER_GEN`` tiers, and they require additional +``CONFIG_TIERS_PER_GEN-2`` bits in ``page->flags``. In contrast to +moving between generations which requires list operations, moving +between tiers only involves operations on ``page->flags`` and +therefore has a negligible cost. A feedback loop modeled after the PID +controller monitors refaulted % across all tiers and decides when to +protect pages from which tiers. + +The framework comprises two conceptually independent components: the +aging and the eviction, which can be invoked separately from user +space for the purpose of working set estimation and proactive reclaim. + +Aging +----- +The aging produces young generations. Given an ``lruvec``, the aging +traverses ``lruvec_memcg()->mm_list`` and calls ``walk_page_range()`` +to scan PTEs for accessed pages (a ``mm_struct`` list is maintained +for each ``memcg``). Upon finding one, the aging updates its +generation number to ``max_seq`` (modulo ``CONFIG_NR_LRU_GENS``). +After each round of traversal, the aging increments ``max_seq``. The +aging is due when ``min_seq[]`` reaches ``max_seq-1``. + +Eviction +-------- +The eviction consumes old generations. Given an ``lruvec``, the +eviction scans pages on the per-zone lists indexed by anon and file +``min_seq[]`` (modulo ``CONFIG_NR_LRU_GENS``). It first tries to +select a type based on the values of ``min_seq[]``. If they are +equal, it selects the type that has a lower refaulted %. The eviction +sorts a page according to its updated generation number if the aging +has found this page accessed. It also moves a page to the next +generation if this page is from an upper tier that has a higher +refaulted % than the base tier. The eviction increments ``min_seq[]`` +of a selected type when it finds all the per-zone lists indexed by +``min_seq[]`` of this selected type are empty. + +To-do List +========== +KVM Optimization +---------------- +Support shadow page table walk. diff --git a/arch/Kconfig b/arch/Kconfig index 8df1c7102643..7392fcc88777 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1288,6 +1288,15 @@ config ARCH_HAS_ELFCORE_COMPAT config ARCH_HAS_PARANOID_L1D_FLUSH bool +config ARCH_HAS_NONLEAF_PMD_YOUNG + bool + depends on PGTABLE_LEVELS > 2 + help + Architectures that select this are able to set the accessed bit on + non-leaf PMD entries in addition to leaf PTE entries where pages are + mapped. For them, page table walkers that clear the accessed bit may + stop at non-leaf PMD entries if they do not see the accessed bit. + source "kernel/gcov/Kconfig" source "scripts/gcc-plugins/Kconfig" diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index ef6be92b1921..99518b4b2a9e 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -779,6 +779,11 @@ static inline bool system_supports_tlb_range(void) cpus_have_const_cap(ARM64_HAS_TLB_RANGE); } +static inline bool system_has_hw_af(void) +{ + return IS_ENABLED(CONFIG_ARM64_HW_AFDBM) && cpus_have_const_cap(ARM64_HW_AF); +} + extern int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt); static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index dfa76afa0ccf..880ae658a69a 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -993,13 +993,16 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, * page after fork() + CoW for pfn mappings. We don't always have a * hardware-managed access flag on arm64. */ -static inline bool arch_faults_on_old_pte(void) +static inline bool arch_has_hw_pte_young(bool local) { - WARN_ON(preemptible()); + if (local) { + WARN_ON(preemptible()); + return cpu_has_hw_af(); + } - return !cpu_has_hw_af(); + return system_has_hw_af(); } -#define arch_faults_on_old_pte arch_faults_on_old_pte +#define arch_has_hw_pte_young arch_has_hw_pte_young /* * Experimentally, it's cheap to set the access flag in hardware and we @@ -1007,7 +1010,7 @@ static inline bool arch_faults_on_old_pte(void) */ static inline bool arch_wants_old_prefaulted_pte(void) { - return !arch_faults_on_old_pte(); + return arch_has_hw_pte_young(true); } #define arch_wants_old_prefaulted_pte arch_wants_old_prefaulted_pte diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6ec7036ef7e1..940615d33845 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2157,6 +2157,16 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .matches = has_hw_dbm, .cpu_enable = cpu_enable_hw_dbm, }, + { + .desc = "Hardware update of the Access flag", + .type = ARM64_CPUCAP_SYSTEM_FEATURE, + .capability = ARM64_HW_AF, + .sys_reg = SYS_ID_AA64MMFR1_EL1, + .sign = FTR_UNSIGNED, + .field_pos = ID_AA64MMFR1_HADBS_SHIFT, + .min_field_value = 1, + .matches = has_cpuid_feature, + }, #endif { .desc = "CRC32 instructions", diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 49305c2e6dfd..d52f50671e60 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -35,6 +35,7 @@ HAS_STAGE2_FWB HAS_SYSREG_GIC_CPUIF HAS_TLB_RANGE HAS_VIRT_HOST_EXTN +HW_AF HW_DBM KVM_PROTECTED_MODE MISMATCHED_CACHE_TYPE diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d9830e7e1060..245742b79be9 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -84,6 +84,7 @@ config X86 select ARCH_HAS_PMEM_API if X86_64 select ARCH_HAS_PTE_DEVMAP if X86_64 select ARCH_HAS_PTE_SPECIAL + select ARCH_HAS_NONLEAF_PMD_YOUNG if X86_64 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 select ARCH_HAS_COPY_MC if X86_64 select ARCH_HAS_SET_MEMORY diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 448cd01eb3ec..36205ec0acac 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -817,7 +817,8 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) static inline int pmd_bad(pmd_t pmd) { - return (pmd_flags(pmd) & ~_PAGE_USER) != _KERNPG_TABLE; + return (pmd_flags(pmd) & ~(_PAGE_USER | _PAGE_ACCESSED)) != + (_KERNPG_TABLE & ~_PAGE_ACCESSED); } static inline unsigned long pages_to_mb(unsigned long npg) @@ -1397,10 +1398,10 @@ static inline bool arch_has_pfn_modify_check(void) return boot_cpu_has_bug(X86_BUG_L1TF); } -#define arch_faults_on_old_pte arch_faults_on_old_pte -static inline bool arch_faults_on_old_pte(void) +#define arch_has_hw_pte_young arch_has_hw_pte_young +static inline bool arch_has_hw_pte_young(bool local) { - return false; + return true; } #endif /* __ASSEMBLY__ */ diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 3481b35cb4ec..a224193d84bf 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -550,7 +550,7 @@ int ptep_test_and_clear_young(struct vm_area_struct *vma, return ret; } -#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) int pmdp_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmdp) { @@ -562,6 +562,9 @@ int pmdp_test_and_clear_young(struct vm_area_struct *vma, return ret; } +#endif + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE int pudp_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pud_t *pudp) { diff --git a/fs/exec.c b/fs/exec.c index a098c133d8d7..c7e55b757e87 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1007,6 +1007,7 @@ static int exec_mmap(struct mm_struct *mm) active_mm = tsk->active_mm; tsk->active_mm = mm; tsk->mm = mm; + lru_gen_add_mm(mm); /* * This prevents preemption while active_mm is being loaded and * it and mm are being updated, which could cause problems for @@ -1017,6 +1018,7 @@ static int exec_mmap(struct mm_struct *mm) if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM)) local_irq_enable(); activate_mm(active_mm, mm); + lru_gen_switch_mm(active_mm, mm); if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM)) local_irq_enable(); tsk->mm->vmacache_seqnum = 0; diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index dde341a6388a..33a2fda7462e 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -785,7 +785,8 @@ static int fuse_check_page(struct page *page) 1 << PG_active | 1 << PG_workingset | 1 << PG_reclaim | - 1 << PG_waiters))) { + 1 << PG_waiters | + LRU_GEN_MASK | LRU_REFS_MASK))) { dump_page(page, "fuse: trying to steal weird page"); return 1; } diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 75c151413fda..b145025f3eac 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -432,6 +432,18 @@ static inline void cgroup_put(struct cgroup *cgrp) css_put(&cgrp->self); } +extern struct mutex cgroup_mutex; + +static inline void cgroup_lock(void) +{ + mutex_lock(&cgroup_mutex); +} + +static inline void cgroup_unlock(void) +{ + mutex_unlock(&cgroup_mutex); +} + /** * task_css_set_check - obtain a task's css_set with extra access conditions * @task: the task to obtain css_set for @@ -446,7 +458,6 @@ static inline void cgroup_put(struct cgroup *cgrp) * as locks used during the cgroup_subsys::attach() methods. */ #ifdef CONFIG_PROVE_RCU -extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; #define task_css_set_check(task, __c) \ rcu_dereference_check((task)->cgroups, \ @@ -707,6 +718,8 @@ struct cgroup; static inline u64 cgroup_id(const struct cgroup *cgrp) { return 1; } static inline void css_get(struct cgroup_subsys_state *css) {} static inline void css_put(struct cgroup_subsys_state *css) {} +static inline void cgroup_lock(void) {} +static inline void cgroup_unlock(void) {} static inline int cgroup_attach_task_all(struct task_struct *from, struct task_struct *t) { return 0; } static inline int cgroupstats_build(struct cgroupstats *stats, diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 3096c9a0ee01..e284a4aa1bd8 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -347,6 +347,10 @@ struct mem_cgroup { struct deferred_split deferred_split_queue; #endif +#ifdef CONFIG_LRU_GEN + struct lru_gen_mm_list mm_list; +#endif + struct mem_cgroup_per_node *nodeinfo[]; }; @@ -1350,10 +1354,13 @@ mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) static inline void lock_page_memcg(struct page *page) { + /* to match page_memcg_rcu() */ + rcu_read_lock(); } static inline void unlock_page_memcg(struct page *page) { + rcu_read_unlock(); } static inline void mem_cgroup_handle_over_high(void) diff --git a/include/linux/mm.h b/include/linux/mm.h index 73a52aba448f..9d3bcc30dfda 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1093,6 +1093,8 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf); #define ZONES_PGOFF (NODES_PGOFF - ZONES_WIDTH) #define LAST_CPUPID_PGOFF (ZONES_PGOFF - LAST_CPUPID_WIDTH) #define KASAN_TAG_PGOFF (LAST_CPUPID_PGOFF - KASAN_TAG_WIDTH) +#define LRU_GEN_PGOFF (KASAN_TAG_PGOFF - LRU_GEN_WIDTH) +#define LRU_REFS_PGOFF (LRU_GEN_PGOFF - LRU_REFS_WIDTH) /* * Define the bit shifts to access each section. For non-existent @@ -1800,6 +1802,40 @@ static inline void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows) { } #endif +#ifdef CONFIG_LRU_GEN +static inline void task_enter_nonseq_fault(void) +{ + WARN_ON(current->in_nonseq_fault); + + current->in_nonseq_fault = 1; +} + +static inline void task_exit_nonseq_fault(void) +{ + WARN_ON(!current->in_nonseq_fault); + + current->in_nonseq_fault = 0; +} + +static inline bool task_in_nonseq_fault(void) +{ + return current->in_nonseq_fault; +} +#else +static inline void task_enter_nonseq_fault(void) +{ +} + +static inline void task_exit_nonseq_fault(void) +{ +} + +static inline bool task_in_nonseq_fault(void) +{ + return false; +} +#endif /* CONFIG_LRU_GEN */ + static inline void unmap_shared_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen) { diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 355ea1ee32bd..7d520f45e612 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -79,11 +79,203 @@ static __always_inline enum lru_list page_lru(struct page *page) return lru; } +#ifdef CONFIG_LRU_GEN + +static inline bool lru_gen_enabled(void) +{ +#ifdef CONFIG_LRU_GEN_ENABLED + DECLARE_STATIC_KEY_TRUE(lru_gen_static_key); + + return static_branch_likely(&lru_gen_static_key); +#else + DECLARE_STATIC_KEY_FALSE(lru_gen_static_key); + + return static_branch_unlikely(&lru_gen_static_key); +#endif +} + +/* Return an index within the sliding window that tracks MAX_NR_GENS generations. */ +static inline int lru_gen_from_seq(unsigned long seq) +{ + return seq % MAX_NR_GENS; +} + +/* Return a proper index regardless whether we keep stats for historical generations. */ +static inline int lru_hist_from_seq(unsigned long seq) +{ + return seq % NR_HIST_GENS; +} + +/* Convert the number of accesses to a tier. See the comment on MAX_NR_TIERS. */ +static inline int lru_tier_from_refs(int refs) +{ + VM_BUG_ON(refs > BIT(LRU_REFS_WIDTH)); + + return order_base_2(refs + 1); +} + +/* The youngest and the second youngest generations are counted as active. */ +static inline bool lru_gen_is_active(struct lruvec *lruvec, int gen) +{ + unsigned long max_seq = lruvec->evictable.max_seq; + + VM_BUG_ON(gen >= MAX_NR_GENS); + + return gen == lru_gen_from_seq(max_seq) || gen == lru_gen_from_seq(max_seq - 1); +} + +/* Update the sizes of the multigenerational lru lists. */ +static inline void lru_gen_update_size(struct page *page, struct lruvec *lruvec, + int old_gen, int new_gen) +{ + int type = page_is_file_lru(page); + int zone = page_zonenum(page); + int delta = thp_nr_pages(page); + enum lru_list lru = type * LRU_FILE; + struct lrugen *lrugen = &lruvec->evictable; + + lockdep_assert_held(&lruvec->lru_lock); + VM_BUG_ON(old_gen != -1 && old_gen >= MAX_NR_GENS); + VM_BUG_ON(new_gen != -1 && new_gen >= MAX_NR_GENS); + VM_BUG_ON(old_gen == -1 && new_gen == -1); + + if (old_gen >= 0) + WRITE_ONCE(lrugen->sizes[old_gen][type][zone], + lrugen->sizes[old_gen][type][zone] - delta); + if (new_gen >= 0) + WRITE_ONCE(lrugen->sizes[new_gen][type][zone], + lrugen->sizes[new_gen][type][zone] + delta); + + if (old_gen < 0) { + if (lru_gen_is_active(lruvec, new_gen)) + lru += LRU_ACTIVE; + update_lru_size(lruvec, lru, zone, delta); + return; + } + + if (new_gen < 0) { + if (lru_gen_is_active(lruvec, old_gen)) + lru += LRU_ACTIVE; + update_lru_size(lruvec, lru, zone, -delta); + return; + } + + if (!lru_gen_is_active(lruvec, old_gen) && lru_gen_is_active(lruvec, new_gen)) { + update_lru_size(lruvec, lru, zone, -delta); + update_lru_size(lruvec, lru + LRU_ACTIVE, zone, delta); + } + + VM_BUG_ON(lru_gen_is_active(lruvec, old_gen) && !lru_gen_is_active(lruvec, new_gen)); +} + +/* Add a page to one of the multigenerational lru lists. Return true on success. */ +static inline bool lru_gen_add_page(struct page *page, struct lruvec *lruvec, bool reclaiming) +{ + int gen; + unsigned long old_flags, new_flags; + int type = page_is_file_lru(page); + int zone = page_zonenum(page); + struct lrugen *lrugen = &lruvec->evictable; + + if (PageUnevictable(page) || !lrugen->enabled[type]) + return false; + /* + * If a page shouldn't be considered for eviction, i.e., a page mapped + * upon fault during which the accessed bit is set, add it to the + * youngest generation. + * + * If a page can't be evicted immediately, i.e., an anon page not in + * swap cache or a dirty page pending writeback, add it to the second + * oldest generation. + * + * If a page could be evicted immediately, e.g., a clean page, add it to + * the oldest generation. + */ + if (PageActive(page)) + gen = lru_gen_from_seq(lrugen->max_seq); + else if ((!type && !PageSwapCache(page)) || + (PageReclaim(page) && (PageDirty(page) || PageWriteback(page)))) + gen = lru_gen_from_seq(lrugen->min_seq[type] + 1); + else + gen = lru_gen_from_seq(lrugen->min_seq[type]); + + do { + new_flags = old_flags = READ_ONCE(page->flags); + VM_BUG_ON_PAGE(new_flags & LRU_GEN_MASK, page); + + new_flags &= ~(LRU_GEN_MASK | BIT(PG_active)); + new_flags |= (gen + 1UL) << LRU_GEN_PGOFF; + } while (cmpxchg(&page->flags, old_flags, new_flags) != old_flags); + + lru_gen_update_size(page, lruvec, -1, gen); + /* for rotate_reclaimable_page() */ + if (reclaiming) + list_add_tail(&page->lru, &lrugen->lists[gen][type][zone]); + else + list_add(&page->lru, &lrugen->lists[gen][type][zone]); + + return true; +} + +/* Delete a page from one of the multigenerational lru lists. Return true on success. */ +static inline bool lru_gen_del_page(struct page *page, struct lruvec *lruvec, bool reclaiming) +{ + int gen; + unsigned long old_flags, new_flags; + + do { + new_flags = old_flags = READ_ONCE(page->flags); + if (!(new_flags & LRU_GEN_MASK)) + return false; + + VM_BUG_ON_PAGE(PageActive(page), page); + VM_BUG_ON_PAGE(PageUnevictable(page), page); + + gen = ((new_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; + + new_flags &= ~LRU_GEN_MASK; + if ((new_flags & LRU_REFS_FLAGS) != LRU_REFS_FLAGS) + new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); + /* for shrink_page_list() */ + if (reclaiming) + new_flags &= ~(BIT(PG_referenced) | BIT(PG_reclaim)); + else if (lru_gen_is_active(lruvec, gen)) + new_flags |= BIT(PG_active); + } while (cmpxchg(&page->flags, old_flags, new_flags) != old_flags); + + lru_gen_update_size(page, lruvec, gen, -1); + list_del(&page->lru); + + return true; +} + +#else + +static inline bool lru_gen_enabled(void) +{ + return false; +} + +static inline bool lru_gen_add_page(struct page *page, struct lruvec *lruvec, bool reclaiming) +{ + return false; +} + +static inline bool lru_gen_del_page(struct page *page, struct lruvec *lruvec, bool reclaiming) +{ + return false; +} + +#endif /* CONFIG_LRU_GEN */ + static __always_inline void add_page_to_lru_list(struct page *page, struct lruvec *lruvec) { enum lru_list lru = page_lru(page); + if (lru_gen_add_page(page, lruvec, false)) + return; + update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page)); list_add(&page->lru, &lruvec->lists[lru]); } @@ -93,6 +285,9 @@ static __always_inline void add_page_to_lru_list_tail(struct page *page, { enum lru_list lru = page_lru(page); + if (lru_gen_add_page(page, lruvec, true)) + return; + update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page)); list_add_tail(&page->lru, &lruvec->lists[lru]); } @@ -100,6 +295,9 @@ static __always_inline void add_page_to_lru_list_tail(struct page *page, static __always_inline void del_page_from_lru_list(struct page *page, struct lruvec *lruvec) { + if (lru_gen_del_page(page, lruvec, false)) + return; + list_del(&page->lru); update_lru_size(lruvec, page_lru(page), page_zonenum(page), -thp_nr_pages(page)); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 7f8ee09c711f..a6ca0607c549 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -15,6 +15,8 @@ #include #include #include +#include +#include #include @@ -580,6 +582,22 @@ struct mm_struct { #ifdef CONFIG_IOMMU_SUPPORT u32 pasid; #endif +#ifdef CONFIG_LRU_GEN + struct { + /* the node of a global or per-memcg mm_struct list */ + struct list_head list; +#ifdef CONFIG_MEMCG + /* points to the memcg of the owner task above */ + struct mem_cgroup *memcg; +#endif + /* whether this mm_struct has been used since the last walk */ + nodemask_t nodes; +#ifndef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH + /* the number of CPUs using this mm_struct */ + atomic_t nr_cpus; +#endif + } lrugen; +#endif /* CONFIG_LRU_GEN */ } __randomize_layout; /* @@ -606,6 +624,94 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm) return (struct cpumask *)&mm->cpu_bitmap; } +#ifdef CONFIG_LRU_GEN + +struct lru_gen_mm_list { + /* a global or per-memcg mm_struct list */ + struct list_head fifo; + /* protects the list above */ + spinlock_t lock; +}; + +void lru_gen_add_mm(struct mm_struct *mm); +void lru_gen_del_mm(struct mm_struct *mm); +#ifdef CONFIG_MEMCG +void lru_gen_migrate_mm(struct mm_struct *mm); +#endif + +static inline void lru_gen_init_mm(struct mm_struct *mm) +{ + INIT_LIST_HEAD(&mm->lrugen.list); +#ifdef CONFIG_MEMCG + mm->lrugen.memcg = NULL; +#endif +#ifndef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH + atomic_set(&mm->lrugen.nr_cpus, 0); +#endif + nodes_clear(mm->lrugen.nodes); +} + +/* Track the usage of each mm_struct so that we can skip inactive ones. */ +static inline void lru_gen_switch_mm(struct mm_struct *old, struct mm_struct *new) +{ + /* exclude init_mm, efi_mm, etc. */ + if (!core_kernel_data((unsigned long)old)) { + nodes_setall(old->lrugen.nodes); +#ifndef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH + atomic_dec(&old->lrugen.nr_cpus); +#endif + } + + if (!core_kernel_data((unsigned long)new)) { + /* unlikely but not a bug when racing with lru_gen_migrate_mm() */ + VM_WARN_ON(list_empty(&new->lrugen.list)); +#ifndef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH + atomic_inc(&new->lrugen.nr_cpus); +#endif + } +} + +/* Return whether this mm_struct is being used on any CPUs. */ +static inline bool lru_gen_mm_is_active(struct mm_struct *mm) +{ +#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH + return !cpumask_empty(mm_cpumask(mm)); +#else + return atomic_read(&mm->lrugen.nr_cpus); +#endif +} + +#else /* !CONFIG_LRU_GEN */ + +static inline void lru_gen_add_mm(struct mm_struct *mm) +{ +} + +static inline void lru_gen_del_mm(struct mm_struct *mm) +{ +} + +#ifdef CONFIG_MEMCG +static inline void lru_gen_migrate_mm(struct mm_struct *mm) +{ +} +#endif + +static inline void lru_gen_init_mm(struct mm_struct *mm) +{ +} + +static inline void lru_gen_switch_mm(struct mm_struct *old, struct mm_struct *new) +{ +} + +static inline bool lru_gen_mm_is_active(struct mm_struct *mm) +{ + return false; +} + +#endif /* CONFIG_LRU_GEN */ + struct mmu_gather; extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm); extern void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm); diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 6a1d79d84675..a7544dc4c91b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -294,6 +294,172 @@ enum lruvec_flags { */ }; +struct lruvec; +struct page_vma_mapped_walk; + +#define LRU_GEN_MASK ((BIT(LRU_GEN_WIDTH) - 1) << LRU_GEN_PGOFF) +#define LRU_REFS_MASK ((BIT(LRU_REFS_WIDTH) - 1) << LRU_REFS_PGOFF) + +#ifdef CONFIG_LRU_GEN + +/* + * For each lruvec, evictable pages are divided into multiple generations. The + * youngest and the oldest generation numbers, AKA max_seq and min_seq, are + * monotonically increasing. The sliding window technique is used to track at + * least MIN_NR_GENS and at most MAX_NR_GENS generations. An offset within the + * window, AKA gen, indexes an array of per-type and per-zone lists for the + * corresponding generation. The counter in page->flags stores gen+1 while a + * page is on one of the multigenerational lru lists. Otherwise, it stores 0. + * + * After a page is faulted in, the aging must check the accessed bit at least + * twice before the eviction would consider it. The first check clears the + * accessed bit set during the initial fault. The second check makes sure this + * page hasn't been used since then. + */ +#define MIN_NR_GENS 2 +#define MAX_NR_GENS ((unsigned int)CONFIG_NR_LRU_GENS) + +/* + * Each generation is divided into multiple tiers. Tiers represent different + * ranges of numbers of accesses from file descriptors, i.e., + * mark_page_accessed(). In contrast to moving between generations which + * requires the lru lock, moving between tiers only involves an atomic + * operation on page->flags and therefore has a negligible cost. + * + * The purposes of tiers are to: + * 1) estimate whether pages accessed multiple times via file descriptors are + * more active than pages accessed only via page tables by separating the two + * access types into upper tiers and the base tier, and comparing refaulted % + * across all tiers. + * 2) improve buffered io performance by deferring the protection of pages + * accessed multiple times until the eviction. That is the protection happens + * in the reclaim path, not the access path. + * + * Pages accessed N times via file descriptors belong to tier order_base_2(N). + * The base tier may be marked by PageReferenced(). All upper tiers are marked + * by PageReferenced() && PageWorkingset(). Additional bits from page->flags are + * used to support more than one upper tier. + */ +#define MAX_NR_TIERS ((unsigned int)CONFIG_TIERS_PER_GEN) +#define LRU_REFS_FLAGS (BIT(PG_referenced) | BIT(PG_workingset)) + +/* Whether to keep stats for historical generations. */ +#ifdef CONFIG_LRU_GEN_STATS +#define NR_HIST_GENS ((unsigned int)CONFIG_NR_LRU_GENS) +#else +#define NR_HIST_GENS 1U +#endif + +struct lrugen { + /* the aging increments the max generation number */ + unsigned long max_seq; + /* the eviction increments the min generation numbers */ + unsigned long min_seq[ANON_AND_FILE]; + /* the birth time of each generation in jiffies */ + unsigned long timestamps[MAX_NR_GENS]; + /* the multigenerational lru lists */ + struct list_head lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; + /* the sizes of the multigenerational lru lists in pages */ + unsigned long sizes[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; + /* the exponential moving average of refaulted */ + unsigned long avg_refaulted[ANON_AND_FILE][MAX_NR_TIERS]; + /* the exponential moving average of protected+evicted */ + unsigned long avg_total[ANON_AND_FILE][MAX_NR_TIERS]; + /* the base tier isn't protected, hence the minus one */ + unsigned long protected[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS - 1]; + /* incremented without holding the lru lock */ + atomic_long_t evicted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; + atomic_long_t refaulted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; + /* whether the multigenerational lru is enabled */ + bool enabled[ANON_AND_FILE]; +}; + +enum { + MM_LEAF_TOTAL, /* total leaf entries */ + MM_LEAF_OLD, /* old leaf entries */ + MM_LEAF_YOUNG, /* young leaf entries */ + MM_NONLEAF_TOTAL, /* total non-leaf entries */ + MM_NONLEAF_PREV, /* previously worthy non-leaf entries */ + MM_NONLEAF_CUR, /* currently worthy non-leaf entries */ + NR_MM_STATS +}; + +/* mnemonic codes for the stats above */ +#define MM_STAT_CODES "toydpc" + +/* double buffering bloom filters */ +#define NR_BLOOM_FILTERS 2 + +struct lru_gen_mm_walk { + /* set to max_seq after each round of walk */ + unsigned long seq; + /* the next mm_struct on the list to walk */ + struct list_head *head; + /* the first mm_struct never walked before */ + struct list_head *tail; + /* to wait for the last walker to finish */ + struct wait_queue_head wait; + /* bloom filters flip after each round of walk */ + unsigned long *filters[NR_BLOOM_FILTERS]; + /* page table stats for debugging */ + unsigned long stats[NR_HIST_GENS][NR_MM_STATS]; + /* the number of concurrent walkers */ + int nr_walkers; +}; + +#define MIN_BATCH_SIZE 64 +#define MAX_BATCH_SIZE 8192 + +struct mm_walk_args { + struct mem_cgroup *memcg; + unsigned long max_seq; + unsigned long start_pfn; + unsigned long end_pfn; + unsigned long next_addr; + unsigned long bitmap[BITS_TO_LONGS(MIN_BATCH_SIZE)]; + int node_id; + int swappiness; + int batch_size; + int nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; + int mm_stats[NR_MM_STATS]; + bool use_filter; +}; + +void lru_gen_init_state(struct mem_cgroup *memcg, struct lruvec *lruvec); +void lru_gen_change_state(bool enable, bool main, bool swap); +void lru_gen_look_around(struct page_vma_mapped_walk *pvmw); + +#ifdef CONFIG_MEMCG +void lru_gen_init_memcg(struct mem_cgroup *memcg); +void lru_gen_free_memcg(struct mem_cgroup *memcg); +#endif + +#else /* !CONFIG_LRU_GEN */ + +static inline void lru_gen_init_state(struct mem_cgroup *memcg, struct lruvec *lruvec) +{ +} + +static inline void lru_gen_change_state(bool enable, bool main, bool swap) +{ +} + +static inline void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) +{ +} + +#ifdef CONFIG_MEMCG +static inline void lru_gen_init_memcg(struct mem_cgroup *memcg) +{ +} + +static inline void lru_gen_free_memcg(struct mem_cgroup *memcg) +{ +} +#endif + +#endif /* CONFIG_LRU_GEN */ + struct lruvec { struct list_head lists[NR_LRU_LISTS]; /* per lruvec lru_lock for memcg */ @@ -311,6 +477,12 @@ struct lruvec { unsigned long refaults[ANON_AND_FILE]; /* Various lruvec state flags (enum lruvec_flags) */ unsigned long flags; +#ifdef CONFIG_LRU_GEN + /* unevictable pages are on LRU_UNEVICTABLE */ + struct lrugen evictable; + /* state for mm list and page table walks */ + struct lru_gen_mm_walk mm_walk; +#endif #ifdef CONFIG_MEMCG struct pglist_data *pgdat; #endif @@ -895,6 +1067,9 @@ typedef struct pglist_data { unsigned long flags; +#ifdef CONFIG_LRU_GEN + struct mm_walk_args mm_walk_args; +#endif ZONE_PADDING(_pad2_) /* Per-node vmstats */ diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h index 567c3ddba2c4..90840c459abc 100644 --- a/include/linux/nodemask.h +++ b/include/linux/nodemask.h @@ -486,6 +486,7 @@ static inline int num_node_state(enum node_states state) #define first_online_node 0 #define first_memory_node 0 #define next_online_node(nid) (MAX_NUMNODES) +#define next_memory_node(nid) (MAX_NUMNODES) #define nr_node_ids 1U #define nr_online_nodes 1U diff --git a/include/linux/oom.h b/include/linux/oom.h index 2db9a1432511..c4c8c7e71099 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -57,6 +57,22 @@ struct oom_control { extern struct mutex oom_lock; extern struct mutex oom_adj_mutex; +#ifdef CONFIG_MMU +extern struct task_struct *oom_reaper_list; +extern struct wait_queue_head oom_reaper_wait; + +static inline bool oom_reaping_in_progress(void) +{ + /* racy check to see if oom reaping could be in progress */ + return READ_ONCE(oom_reaper_list) || !waitqueue_active(&oom_reaper_wait); +} +#else +static inline bool oom_reaping_in_progress(void) +{ + return false; +} +#endif + static inline void set_current_oom_origin(void) { current->signal->oom_flag_origin = true; diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h index ef1e3e736e14..8cdbbdccb5ad 100644 --- a/include/linux/page-flags-layout.h +++ b/include/linux/page-flags-layout.h @@ -26,6 +26,14 @@ #define ZONES_WIDTH ZONES_SHIFT +#ifdef CONFIG_LRU_GEN +/* LRU_GEN_WIDTH is generated from order_base_2(CONFIG_NR_LRU_GENS + 1). */ +#define LRU_REFS_WIDTH (CONFIG_TIERS_PER_GEN - 2) +#else +#define LRU_GEN_WIDTH 0 +#define LRU_REFS_WIDTH 0 +#endif /* CONFIG_LRU_GEN */ + #ifdef CONFIG_SPARSEMEM #include #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) @@ -55,7 +63,8 @@ #define SECTIONS_WIDTH 0 #endif -#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS +#if ZONES_WIDTH + LRU_GEN_WIDTH + LRU_REFS_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \ + <= BITS_PER_LONG - NR_PAGEFLAGS #define NODES_WIDTH NODES_SHIFT #elif defined(CONFIG_SPARSEMEM_VMEMMAP) #error "Vmemmap: No space for nodes field in page flags" @@ -89,8 +98,8 @@ #define LAST_CPUPID_SHIFT 0 #endif -#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT \ - <= BITS_PER_LONG - NR_PAGEFLAGS +#if ZONES_WIDTH + LRU_GEN_WIDTH + LRU_REFS_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ + KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT #else #define LAST_CPUPID_WIDTH 0 @@ -100,8 +109,8 @@ #define LAST_CPUPID_NOT_IN_PAGE_FLAGS #endif -#if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH \ - > BITS_PER_LONG - NR_PAGEFLAGS +#if ZONES_WIDTH + LRU_GEN_WIDTH + LRU_REFS_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ + KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS #error "Not enough bits in page flags" #endif diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index fbfd3fad48f2..a7d7ff4c621d 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -845,7 +845,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page) 1UL << PG_private | 1UL << PG_private_2 | \ 1UL << PG_writeback | 1UL << PG_reserved | \ 1UL << PG_slab | 1UL << PG_active | \ - 1UL << PG_unevictable | __PG_MLOCKED) + 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK) /* * Flags checked when a page is prepped for return by the page allocator. @@ -856,7 +856,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page) * alloc-free cycle to prevent from reusing the page. */ #define PAGE_FLAGS_CHECK_AT_PREP \ - (PAGEFLAGS_MASK & ~__PG_HWPOISON) + ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK) #define PAGE_FLAGS_PRIVATE \ (1UL << PG_private | 1UL << PG_private_2) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index e24d2c992b11..afb9004b778a 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -211,7 +211,7 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, #endif #ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG -#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp) @@ -232,7 +232,7 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, BUILD_BUG(); return 0; } -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ +#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */ #endif #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH @@ -258,6 +258,19 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma, #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif +#ifndef arch_has_hw_pte_young +/* + * Return whether the accessed bit is supported by the local CPU or all CPUs. + * + * Those arches which have hw access flag feature need to implement their own + * helper. By default, "false" means pagefault will be hit on old pte. + */ +static inline bool arch_has_hw_pte_young(bool local) +{ + return false; +} +#endif + #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long address, diff --git a/include/linux/sched.h b/include/linux/sched.h index c1a927ddec64..556b3d66c70d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -911,6 +911,9 @@ struct task_struct { #ifdef CONFIG_MEMCG unsigned in_user_fault:1; #endif +#ifdef CONFIG_LRU_GEN + unsigned in_nonseq_fault:1; +#endif #ifdef CONFIG_COMPAT_BRK unsigned brk_randomized:1; #endif diff --git a/include/linux/swap.h b/include/linux/swap.h index ba52f3a3478e..2c4a5a88f83c 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -137,6 +137,9 @@ union swap_header { */ struct reclaim_state { unsigned long reclaimed_slab; +#ifdef CONFIG_LRU_GEN + struct mm_walk_args *mm_walk_args; +#endif }; #ifdef __KERNEL__ diff --git a/kernel/bounds.c b/kernel/bounds.c index 9795d75b09b2..aba13aa7336c 100644 --- a/kernel/bounds.c +++ b/kernel/bounds.c @@ -22,6 +22,9 @@ int main(void) DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS)); #endif DEFINE(SPINLOCK_SIZE, sizeof(spinlock_t)); +#ifdef CONFIG_LRU_GEN + DEFINE(LRU_GEN_WIDTH, order_base_2(CONFIG_NR_LRU_GENS + 1)); +#endif /* End of constants */ return 0; diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index bfbeabc17a9d..bec59189e206 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -146,7 +146,6 @@ struct cgroup_mgctx { #define DEFINE_CGROUP_MGCTX(name) \ struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name) -extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; extern struct cgroup_subsys *cgroup_subsys[]; extern struct list_head cgroup_roots; diff --git a/kernel/exit.c b/kernel/exit.c index 91a43e57a32e..788a299abb4e 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -422,6 +422,7 @@ void mm_update_next_owner(struct mm_struct *mm) goto retry; } WRITE_ONCE(mm->owner, c); + lru_gen_migrate_mm(mm); task_unlock(c); put_task_struct(c); } diff --git a/kernel/fork.c b/kernel/fork.c index 38681ad44c76..8d6bb4e76904 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -681,6 +681,7 @@ static void check_mm(struct mm_struct *mm) #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS VM_BUG_ON_MM(mm->pmd_huge_pte, mm); #endif + VM_BUG_ON_MM(lru_gen_mm_is_active(mm), mm); } #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) @@ -1080,6 +1081,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, goto fail_nocontext; mm->user_ns = get_user_ns(user_ns); + lru_gen_init_mm(mm); return mm; fail_nocontext: @@ -1122,6 +1124,7 @@ static inline void __mmput(struct mm_struct *mm) } if (mm->binfmt) module_put(mm->binfmt->module); + lru_gen_del_mm(mm); mmdrop(mm); } @@ -2605,6 +2608,13 @@ pid_t kernel_clone(struct kernel_clone_args *args) get_task_struct(p); } + if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) { + /* lock the task to synchronize with memcg migration */ + task_lock(p); + lru_gen_add_mm(p->mm); + task_unlock(p); + } + wake_up_new_task(p); /* forking complete and child started to run, tell ptracer */ diff --git a/kernel/kthread.c b/kernel/kthread.c index 5b37a8567168..fd827fdad26b 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1361,6 +1361,7 @@ void kthread_use_mm(struct mm_struct *mm) tsk->mm = mm; membarrier_update_current_mm(mm); switch_mm_irqs_off(active_mm, mm, tsk); + lru_gen_switch_mm(active_mm, mm); local_irq_enable(); task_unlock(tsk); #ifdef finish_arch_post_lock_switch diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f21714ea3db8..e5e4cc86e296 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4924,6 +4924,7 @@ context_switch(struct rq *rq, struct task_struct *prev, * finish_task_switch()'s mmdrop(). */ switch_mm_irqs_off(prev->active_mm, next->mm, next); + lru_gen_switch_mm(prev->active_mm, next->mm); if (!prev->mm) { // from kernel /* will mmdrop() in finish_task_switch(). */ @@ -8792,6 +8793,7 @@ void idle_task_exit(void) if (mm != &init_mm) { switch_mm(mm, &init_mm, current); + lru_gen_switch_mm(mm, &init_mm); finish_arch_post_lock_switch(); } diff --git a/mm/Kconfig b/mm/Kconfig index d16ba9249bc5..48e7babb22e5 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -896,4 +896,63 @@ config SECRETMEM source "mm/damon/Kconfig" +# the multigenerational lru { +config LRU_GEN + bool "Multigenerational LRU" + depends on MMU + # the following options may leave not enough spare bits in page->flags + depends on !MAXSMP && (64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP) + help + A high performance LRU implementation to heavily overcommit workloads + that are not IO bound. See Documentation/vm/multigen_lru.rst for + details. + + Warning: do not enable this option unless you plan to use it because + it introduces a small per-process and per-memcg and per-node memory + overhead. + +config LRU_GEN_ENABLED + bool "Turn on by default" + depends on LRU_GEN + help + The default value of /sys/kernel/mm/lru_gen/enabled is 0. This option + changes it to 1. + + Warning: the default value is the fast path. See + Documentation/static-keys.txt for details. + +config LRU_GEN_STATS + bool "Full stats for debugging" + depends on LRU_GEN + help + This option keeps full stats for each generation, which can be read + from /sys/kernel/debug/lru_gen_full. + + Warning: do not enable this option unless you plan to use it because + it introduces an additional small per-process and per-memcg and + per-node memory overhead. + +config NR_LRU_GENS + int "Max number of generations" + depends on LRU_GEN + range 4 31 + default 7 + help + This will use order_base_2(N+1) spare bits from page flags. + + Warning: do not use numbers larger than necessary because each + generation introduces a small per-node and per-memcg memory overhead. + +config TIERS_PER_GEN + int "Number of tiers per generation" + depends on LRU_GEN + range 2 5 + default 4 + help + This will use N-2 spare bits from page flags. + + Larger values generally offer better protection to active pages under + heavy buffered I/O workloads. +# } + endmenu diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c5142d237e48..875ed5559d95 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2364,7 +2364,8 @@ static void __split_huge_page_tail(struct page *head, int tail, #ifdef CONFIG_64BIT (1L << PG_arch_2) | #endif - (1L << PG_dirty))); + (1L << PG_dirty) | + LRU_GEN_MASK | LRU_REFS_MASK)); /* ->mapping in first tail page is compound_mapcount */ VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6da5020a8656..49100d053e3b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1239,12 +1239,17 @@ void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, *lru_size += nr_pages; size = *lru_size; +#ifdef CONFIG_LRU_GEN + /* unlikely but not a bug when reset_batch_size() is pending */ + VM_WARN_ON(size + MAX_BATCH_SIZE < 0); +#else if (WARN_ONCE(size < 0, "%s(%p, %d, %d): lru_size %ld\n", __func__, lruvec, lru, nr_pages, size)) { VM_BUG_ON(1); *lru_size = 0; } +#endif if (nr_pages > 0) *lru_size += nr_pages; @@ -5110,6 +5115,7 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) static void mem_cgroup_free(struct mem_cgroup *memcg) { + lru_gen_free_memcg(memcg); memcg_wb_domain_exit(memcg); __mem_cgroup_free(memcg); } @@ -5173,6 +5179,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) memcg->deferred_split_queue.split_queue_len = 0; #endif idr_replace(&mem_cgroup_idr, memcg, memcg->id.id); + lru_gen_init_memcg(memcg); return memcg; fail: mem_cgroup_id_remove(memcg); @@ -6156,6 +6163,29 @@ static void mem_cgroup_move_task(void) } #endif +#ifdef CONFIG_LRU_GEN +static void mem_cgroup_attach(struct cgroup_taskset *tset) +{ + struct cgroup_subsys_state *css; + struct task_struct *task = NULL; + + cgroup_taskset_for_each_leader(task, css, tset) + break; + + if (!task) + return; + + task_lock(task); + if (task->mm && task->mm->owner == task) + lru_gen_migrate_mm(task->mm); + task_unlock(task); +} +#else +static void mem_cgroup_attach(struct cgroup_taskset *tset) +{ +} +#endif /* CONFIG_LRU_GEN */ + static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value) { if (value == PAGE_COUNTER_MAX) @@ -6499,6 +6529,7 @@ struct cgroup_subsys memory_cgrp_subsys = { .css_reset = mem_cgroup_css_reset, .css_rstat_flush = mem_cgroup_css_rstat_flush, .can_attach = mem_cgroup_can_attach, + .attach = mem_cgroup_attach, .cancel_attach = mem_cgroup_cancel_attach, .post_attach = mem_cgroup_move_task, .dfl_cftypes = memory_files, diff --git a/mm/memory.c b/mm/memory.c index c52be6d6b605..6b2b665c0866 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -121,18 +121,6 @@ int randomize_va_space __read_mostly = 2; #endif -#ifndef arch_faults_on_old_pte -static inline bool arch_faults_on_old_pte(void) -{ - /* - * Those arches which don't have hw access flag feature need to - * implement their own helper. By default, "true" means pagefault - * will be hit on old pte. - */ - return true; -} -#endif - #ifndef arch_wants_old_prefaulted_pte static inline bool arch_wants_old_prefaulted_pte(void) { @@ -2769,7 +2757,7 @@ static inline bool cow_user_page(struct page *dst, struct page *src, * On architectures with software "accessed" bits, we would * take a double page fault, so mark it accessed here. */ - if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) { + if (!arch_has_hw_pte_young(true) && !pte_young(vmf->orig_pte)) { pte_t entry; vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); @@ -4774,6 +4762,7 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, unsigned int flags, struct pt_regs *regs) { vm_fault_t ret; + bool nonseq_fault = !(vma->vm_flags & VM_SEQ_READ); __set_current_state(TASK_RUNNING); @@ -4795,11 +4784,17 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, if (flags & FAULT_FLAG_USER) mem_cgroup_enter_user_fault(); + if (nonseq_fault) + task_enter_nonseq_fault(); + if (unlikely(is_vm_hugetlb_page(vma))) ret = hugetlb_fault(vma->vm_mm, vma, address, flags); else ret = __handle_mm_fault(vma, address, flags); + if (nonseq_fault) + task_exit_nonseq_fault(); + if (flags & FAULT_FLAG_USER) { mem_cgroup_exit_user_fault(); /* diff --git a/mm/mm_init.c b/mm/mm_init.c index 9ddaf0e1b0ab..0d7b2bd2454a 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -65,14 +65,16 @@ void __init mminit_verify_pageflags_layout(void) shift = 8 * sizeof(unsigned long); width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH - - LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH; + - LAST_CPUPID_SHIFT - KASAN_TAG_WIDTH - LRU_GEN_WIDTH - LRU_REFS_WIDTH; mminit_dprintk(MMINIT_TRACE, "pageflags_layout_widths", - "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Flags %d\n", + "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d Gen %d Tier %d Flags %d\n", SECTIONS_WIDTH, NODES_WIDTH, ZONES_WIDTH, LAST_CPUPID_WIDTH, KASAN_TAG_WIDTH, + LRU_GEN_WIDTH, + LRU_REFS_WIDTH, NR_PAGEFLAGS); mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts", "Section %d Node %d Zone %d Lastcpupid %d Kasantag %d\n", diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 989f35a2bbb1..72855b7bde09 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -508,8 +508,8 @@ bool process_shares_mm(struct task_struct *p, struct mm_struct *mm) * victim (if that is possible) to help the OOM killer to move on. */ static struct task_struct *oom_reaper_th; -static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait); -static struct task_struct *oom_reaper_list; +DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait); +struct task_struct *oom_reaper_list; static DEFINE_SPINLOCK(oom_reaper_lock); bool __oom_reap_task_mm(struct mm_struct *mm) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 23d3339ac4e8..5bee46999f60 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7405,6 +7405,7 @@ static void __meminit pgdat_init_internals(struct pglist_data *pgdat) pgdat_page_ext_init(pgdat); lruvec_init(&pgdat->__lruvec); + lru_gen_init_state(NULL, &pgdat->__lruvec); } static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid, diff --git a/mm/rmap.c b/mm/rmap.c index 6aebd1747251..a6b522fe871a 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -73,6 +73,7 @@ #include #include #include +#include #include @@ -790,6 +791,13 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, } if (pvmw.pte) { + /* the multigenerational lru exploits the spatial locality */ + if (lru_gen_enabled() && pte_young(*pvmw.pte) && + !(vma->vm_flags & VM_SEQ_READ)) { + lru_gen_look_around(&pvmw); + referenced++; + } + if (ptep_clear_flush_young_notify(vma, address, pvmw.pte)) { /* diff --git a/mm/swap.c b/mm/swap.c index af3cad4e5378..93f5fe5f99ca 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -389,6 +389,43 @@ static void __lru_cache_activate_page(struct page *page) local_unlock(&lru_pvecs.lock); } +#ifdef CONFIG_LRU_GEN +static void page_inc_refs(struct page *page) +{ + unsigned long refs; + unsigned long old_flags, new_flags; + + if (PageUnevictable(page)) + return; + + /* see the comment on MAX_NR_TIERS */ + do { + new_flags = old_flags = READ_ONCE(page->flags); + + if (!(new_flags & BIT(PG_referenced))) { + new_flags |= BIT(PG_referenced); + continue; + } + + if (!(new_flags & BIT(PG_workingset))) { + new_flags |= BIT(PG_workingset); + continue; + } + + refs = new_flags & LRU_REFS_MASK; + refs = min(refs + BIT(LRU_REFS_PGOFF), LRU_REFS_MASK); + + new_flags &= ~LRU_REFS_MASK; + new_flags |= refs; + } while (new_flags != old_flags && + cmpxchg(&page->flags, old_flags, new_flags) != old_flags); +} +#else +static void page_inc_refs(struct page *page) +{ +} +#endif /* CONFIG_LRU_GEN */ + /* * Mark a page as having seen activity. * @@ -403,6 +440,11 @@ void mark_page_accessed(struct page *page) { page = compound_head(page); + if (lru_gen_enabled()) { + page_inc_refs(page); + return; + } + if (!PageReferenced(page)) { SetPageReferenced(page); } else if (PageUnevictable(page)) { @@ -446,6 +488,11 @@ void lru_cache_add(struct page *page) VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page); VM_BUG_ON_PAGE(PageLRU(page), page); + /* see the comment in lru_gen_add_page() */ + if (lru_gen_enabled() && !PageUnevictable(page) && + task_in_nonseq_fault() && !(current->flags & PF_MEMALLOC)) + SetPageActive(page); + get_page(page); local_lock(&lru_pvecs.lock); pvec = this_cpu_ptr(&lru_pvecs.lru_add); @@ -547,7 +594,7 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec) static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec) { - if (PageActive(page) && !PageUnevictable(page)) { + if (!PageUnevictable(page) && (PageActive(page) || lru_gen_enabled())) { int nr_pages = thp_nr_pages(page); del_page_from_lru_list(page, lruvec); @@ -661,7 +708,7 @@ void deactivate_file_page(struct page *page) */ void deactivate_page(struct page *page) { - if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { + if (PageLRU(page) && !PageUnevictable(page) && (PageActive(page) || lru_gen_enabled())) { struct pagevec *pvec; local_lock(&lru_pvecs.lock); diff --git a/mm/swapfile.c b/mm/swapfile.c index 22d10f713848..2ac9ac0b5ec3 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2688,6 +2688,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) err = 0; atomic_inc(&proc_poll_event); wake_up_interruptible(&proc_poll_wait); + lru_gen_change_state(false, false, true); out_dput: filp_close(victim, NULL); @@ -3349,6 +3350,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) mutex_unlock(&swapon_mutex); atomic_inc(&proc_poll_event); wake_up_interruptible(&proc_poll_wait); + lru_gen_change_state(true, false, true); error = 0; goto out; diff --git a/mm/vmscan.c b/mm/vmscan.c index 74296c2d1fed..7c3a49173902 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -50,6 +50,11 @@ #include #include #include +#include +#include +#include +#include +#include #include #include @@ -1142,9 +1147,11 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, if (PageSwapCache(page)) { swp_entry_t swap = { .val = page_private(page) }; - mem_cgroup_swapout(page, swap); + + /* get a shadow entry before page_memcg() is cleared */ if (reclaimed && !mapping_exiting(mapping)) shadow = workingset_eviction(page, target_memcg); + mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page, swap, shadow); xa_unlock_irq(&mapping->i_pages); put_swap_page(page, swap); @@ -1407,6 +1414,11 @@ static unsigned int shrink_page_list(struct list_head *page_list, if (!sc->may_unmap && page_mapped(page)) goto keep_locked; + /* lru_gen_look_around() has updated this page? */ + if (lru_gen_enabled() && !ignore_references && + page_mapped(page) && PageReferenced(page)) + goto keep_locked; + may_enter_fs = (sc->gfp_mask & __GFP_FS) || (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); @@ -2562,6 +2574,106 @@ enum scan_balance { SCAN_FILE, }; +static void prepare_scan_count(pg_data_t *pgdat, struct scan_control *sc) +{ + unsigned long file; + struct lruvec *target_lruvec; + + if (lru_gen_enabled()) + return; + + target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat); + + /* + * Determine the scan balance between anon and file LRUs. + */ + spin_lock_irq(&target_lruvec->lru_lock); + sc->anon_cost = target_lruvec->anon_cost; + sc->file_cost = target_lruvec->file_cost; + spin_unlock_irq(&target_lruvec->lru_lock); + + /* + * Target desirable inactive:active list ratios for the anon + * and file LRU lists. + */ + if (!sc->force_deactivate) { + unsigned long refaults; + + refaults = lruvec_page_state(target_lruvec, + WORKINGSET_ACTIVATE_ANON); + if (refaults != target_lruvec->refaults[0] || + inactive_is_low(target_lruvec, LRU_INACTIVE_ANON)) + sc->may_deactivate |= DEACTIVATE_ANON; + else + sc->may_deactivate &= ~DEACTIVATE_ANON; + + /* + * When refaults are being observed, it means a new + * workingset is being established. Deactivate to get + * rid of any stale active pages quickly. + */ + refaults = lruvec_page_state(target_lruvec, + WORKINGSET_ACTIVATE_FILE); + if (refaults != target_lruvec->refaults[1] || + inactive_is_low(target_lruvec, LRU_INACTIVE_FILE)) + sc->may_deactivate |= DEACTIVATE_FILE; + else + sc->may_deactivate &= ~DEACTIVATE_FILE; + } else + sc->may_deactivate = DEACTIVATE_ANON | DEACTIVATE_FILE; + + /* + * If we have plenty of inactive file pages that aren't + * thrashing, try to reclaim those first before touching + * anonymous pages. + */ + file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE); + if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE)) + sc->cache_trim_mode = 1; + else + sc->cache_trim_mode = 0; + + /* + * Prevent the reclaimer from falling into the cache trap: as + * cache pages start out inactive, every cache fault will tip + * the scan balance towards the file LRU. And as the file LRU + * shrinks, so does the window for rotation from references. + * This means we have a runaway feedback loop where a tiny + * thrashing file LRU becomes infinitely more attractive than + * anon pages. Try to detect this based on file LRU size. + */ + if (!cgroup_reclaim(sc)) { + unsigned long total_high_wmark = 0; + unsigned long free, anon; + int z; + + free = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); + file = node_page_state(pgdat, NR_ACTIVE_FILE) + + node_page_state(pgdat, NR_INACTIVE_FILE); + + for (z = 0; z < MAX_NR_ZONES; z++) { + struct zone *zone = &pgdat->node_zones[z]; + + if (!managed_zone(zone)) + continue; + + total_high_wmark += high_wmark_pages(zone); + } + + /* + * Consider anon: if that's low too, this isn't a + * runaway file reclaim problem, but rather just + * extreme pressure. Reclaim as per usual then. + */ + anon = node_page_state(pgdat, NR_INACTIVE_ANON); + + sc->file_is_tiny = + file + free <= total_high_wmark && + !(sc->may_deactivate & DEACTIVATE_ANON) && + anon >> sc->priority; + } +} + /* * Determine how aggressively the anon and file LRU lists should be * scanned. The relative value of each set of LRU lists is determined @@ -2783,6 +2895,2487 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, return can_demote(pgdat->node_id, sc); } +#ifdef CONFIG_LRU_GEN + +/****************************************************************************** + * shorthand helpers + ******************************************************************************/ + +#define DEFINE_MAX_SEQ(lruvec) \ + unsigned long max_seq = READ_ONCE((lruvec)->evictable.max_seq) + +#define DEFINE_MIN_SEQ(lruvec) \ + unsigned long min_seq[ANON_AND_FILE] = { \ + READ_ONCE((lruvec)->evictable.min_seq[0]), \ + READ_ONCE((lruvec)->evictable.min_seq[1]), \ + } + +#define for_each_gen_type_zone(gen, type, zone) \ + for ((gen) = 0; (gen) < MAX_NR_GENS; (gen)++) \ + for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \ + for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++) + +static int page_lru_gen(struct page *page) +{ + unsigned long flags = READ_ONCE(page->flags); + + return ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; +} + +static int page_lru_tier(struct page *page) +{ + int refs; + unsigned long flags = READ_ONCE(page->flags); + + refs = (flags & LRU_REFS_FLAGS) == LRU_REFS_FLAGS ? + ((flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF) + 1 : 0; + + return lru_tier_from_refs(refs); +} + +static int get_swappiness(struct mem_cgroup *memcg) +{ + return mem_cgroup_get_nr_swap_pages(memcg) >= MIN_BATCH_SIZE ? + mem_cgroup_swappiness(memcg) : 0; +} + +static struct lruvec *get_lruvec(int nid, struct mem_cgroup *memcg) +{ + struct pglist_data *pgdat = NODE_DATA(nid); + +#ifdef CONFIG_MEMCG + if (memcg) + return &memcg->nodeinfo[nid]->lruvec; +#endif + return pgdat ? &pgdat->__lruvec : NULL; +} + +static int get_nr_gens(struct lruvec *lruvec, int type) +{ + return lruvec->evictable.max_seq - lruvec->evictable.min_seq[type] + 1; +} + +static bool __maybe_unused seq_is_valid(struct lruvec *lruvec) +{ + return get_nr_gens(lruvec, 1) >= MIN_NR_GENS && + get_nr_gens(lruvec, 1) <= get_nr_gens(lruvec, 0) && + get_nr_gens(lruvec, 0) <= MAX_NR_GENS; +} + +/****************************************************************************** + * mm_struct list + ******************************************************************************/ + +static struct lru_gen_mm_list *get_mm_list(struct mem_cgroup *memcg) +{ + static struct lru_gen_mm_list mm_list = { + .fifo = LIST_HEAD_INIT(mm_list.fifo), + .lock = __SPIN_LOCK_UNLOCKED(mm_list.lock), + }; + +#ifdef CONFIG_MEMCG + if (memcg) + return &memcg->mm_list; +#endif + return &mm_list; +} + +void lru_gen_add_mm(struct mm_struct *mm) +{ + int nid; + struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm); + struct lru_gen_mm_list *mm_list = get_mm_list(memcg); + + VM_BUG_ON_MM(!list_empty(&mm->lrugen.list), mm); +#ifdef CONFIG_MEMCG + VM_BUG_ON_MM(mm->lrugen.memcg, mm); + mm->lrugen.memcg = memcg; +#endif + spin_lock(&mm_list->lock); + + list_add_tail(&mm->lrugen.list, &mm_list->fifo); + + for_each_node(nid) { + struct lruvec *lruvec = get_lruvec(nid, memcg); + + if (!lruvec) + continue; + + if (lruvec->mm_walk.tail == &mm_list->fifo) + lruvec->mm_walk.tail = lruvec->mm_walk.tail->prev; + } + + spin_unlock(&mm_list->lock); +} + +void lru_gen_del_mm(struct mm_struct *mm) +{ + int nid; + struct lru_gen_mm_list *mm_list; + struct mem_cgroup *memcg = NULL; + + if (list_empty(&mm->lrugen.list)) + return; + +#ifdef CONFIG_MEMCG + memcg = mm->lrugen.memcg; +#endif + mm_list = get_mm_list(memcg); + + spin_lock(&mm_list->lock); + + for_each_node(nid) { + struct lruvec *lruvec = get_lruvec(nid, memcg); + + if (!lruvec) + continue; + + if (lruvec->mm_walk.tail == &mm->lrugen.list) + lruvec->mm_walk.tail = lruvec->mm_walk.tail->next; + + if (lruvec->mm_walk.head != &mm->lrugen.list) + continue; + + lruvec->mm_walk.head = lruvec->mm_walk.head->next; + if (lruvec->mm_walk.head == &mm_list->fifo) + WRITE_ONCE(lruvec->mm_walk.seq, lruvec->mm_walk.seq + 1); + } + + list_del_init(&mm->lrugen.list); + + spin_unlock(&mm_list->lock); + +#ifdef CONFIG_MEMCG + mem_cgroup_put(mm->lrugen.memcg); + mm->lrugen.memcg = NULL; +#endif +} + +#ifdef CONFIG_MEMCG +void lru_gen_migrate_mm(struct mm_struct *mm) +{ + struct mem_cgroup *memcg; + + lockdep_assert_held(&mm->owner->alloc_lock); + + if (mem_cgroup_disabled()) + return; + + rcu_read_lock(); + memcg = mem_cgroup_from_task(mm->owner); + rcu_read_unlock(); + if (memcg == mm->lrugen.memcg) + return; + + VM_BUG_ON_MM(!mm->lrugen.memcg, mm); + VM_BUG_ON_MM(list_empty(&mm->lrugen.list), mm); + + lru_gen_del_mm(mm); + lru_gen_add_mm(mm); +} +#endif + +#define BLOOM_FILTER_SHIFT 15 + +static inline int filter_gen_from_seq(unsigned long seq) +{ + return seq % NR_BLOOM_FILTERS; +} + +static void get_item_key(void *item, int *key) +{ + u32 hash = hash_ptr(item, BLOOM_FILTER_SHIFT * 2); + + BUILD_BUG_ON(BLOOM_FILTER_SHIFT * 2 > BITS_PER_TYPE(u32)); + + key[0] = hash & (BIT(BLOOM_FILTER_SHIFT) - 1); + key[1] = hash >> BLOOM_FILTER_SHIFT; +} + +static void clear_bloom_filter(struct lruvec *lruvec, unsigned long seq) +{ + unsigned long *filter; + int gen = filter_gen_from_seq(seq); + + lockdep_assert_held(&get_mm_list(lruvec_memcg(lruvec))->lock); + + filter = lruvec->mm_walk.filters[gen]; + if (filter) { + bitmap_clear(filter, 0, BIT(BLOOM_FILTER_SHIFT)); + return; + } + + filter = bitmap_zalloc(BIT(BLOOM_FILTER_SHIFT), GFP_ATOMIC); + WRITE_ONCE(lruvec->mm_walk.filters[gen], filter); +} + +static void set_bloom_filter(struct lruvec *lruvec, unsigned long seq, void *item) +{ + int key[2]; + unsigned long *filter; + int gen = filter_gen_from_seq(seq); + + filter = READ_ONCE(lruvec->mm_walk.filters[gen]); + if (!filter) + return; + + get_item_key(item, key); + + if (!test_bit(key[0], filter)) + set_bit(key[0], filter); + if (!test_bit(key[1], filter)) + set_bit(key[1], filter); +} + +static bool test_bloom_filter(struct lruvec *lruvec, unsigned long seq, void *item) +{ + int key[2]; + unsigned long *filter; + int gen = filter_gen_from_seq(seq); + + filter = READ_ONCE(lruvec->mm_walk.filters[gen]); + if (!filter) + return false; + + get_item_key(item, key); + + return test_bit(key[0], filter) && test_bit(key[1], filter); +} + +static void reset_mm_stats(struct lruvec *lruvec, bool last, struct mm_walk_args *args) +{ + int i; + int hist = lru_hist_from_seq(args->max_seq); + + lockdep_assert_held(&get_mm_list(lruvec_memcg(lruvec))->lock); + + for (i = 0; i < NR_MM_STATS; i++) { + WRITE_ONCE(lruvec->mm_walk.stats[hist][i], + lruvec->mm_walk.stats[hist][i] + args->mm_stats[i]); + args->mm_stats[i] = 0; + } + + if (!last || NR_HIST_GENS == 1) + return; + + hist = lru_hist_from_seq(args->max_seq + 1); + for (i = 0; i < NR_MM_STATS; i++) + WRITE_ONCE(lruvec->mm_walk.stats[hist][i], 0); +} + +static bool should_skip_mm(struct mm_struct *mm, struct mm_walk_args *args) +{ + int type; + unsigned long size = 0; + + if (!lru_gen_mm_is_active(mm) && !node_isset(args->node_id, mm->lrugen.nodes)) + return true; + + if (mm_is_oom_victim(mm)) + return true; + + for (type = !args->swappiness; type < ANON_AND_FILE; type++) { + size += type ? get_mm_counter(mm, MM_FILEPAGES) : + get_mm_counter(mm, MM_ANONPAGES) + + get_mm_counter(mm, MM_SHMEMPAGES); + } + + if (size < MIN_BATCH_SIZE) + return true; + + if (!mmget_not_zero(mm)) + return true; + + node_clear(args->node_id, mm->lrugen.nodes); + + return false; +} + +/* To support multiple walkers that concurrently walk an mm_struct list. */ +static bool get_next_mm(struct lruvec *lruvec, struct mm_walk_args *args, + struct mm_struct **iter) +{ + bool first = false; + bool last = true; + struct mm_struct *mm = NULL; + struct lru_gen_mm_walk *mm_walk = &lruvec->mm_walk; + struct lru_gen_mm_list *mm_list = get_mm_list(args->memcg); + + if (*iter) + mmput_async(*iter); + else if (args->max_seq <= READ_ONCE(mm_walk->seq)) + return false; + + spin_lock(&mm_list->lock); + + VM_BUG_ON(args->max_seq > mm_walk->seq + 1); + VM_BUG_ON(*iter && args->max_seq < mm_walk->seq); + VM_BUG_ON(*iter && !mm_walk->nr_walkers); + + if (args->max_seq <= mm_walk->seq) { + if (!*iter) + last = false; + goto done; + } + + if (mm_walk->head == &mm_list->fifo) { + VM_BUG_ON(mm_walk->nr_walkers); + mm_walk->head = mm_walk->head->next; + first = true; + } + + while (!mm && mm_walk->head != &mm_list->fifo) { + mm = list_entry(mm_walk->head, struct mm_struct, lrugen.list); + + mm_walk->head = mm_walk->head->next; + + if (mm_walk->tail == &mm->lrugen.list) { + mm_walk->tail = mm_walk->tail->next; + args->use_filter = false; + } + + if (should_skip_mm(mm, args)) + mm = NULL; + } + + if (mm_walk->head == &mm_list->fifo) + WRITE_ONCE(mm_walk->seq, mm_walk->seq + 1); +done: + if (*iter && !mm) + mm_walk->nr_walkers--; + if (!*iter && mm) + mm_walk->nr_walkers++; + + if (mm_walk->nr_walkers) + last = false; + + if (mm && first) + clear_bloom_filter(lruvec, args->max_seq + 1); + + if (*iter || last) + reset_mm_stats(lruvec, last, args); + + spin_unlock(&mm_list->lock); + + *iter = mm; + + return last; +} + +/****************************************************************************** + * refault feedback loop + ******************************************************************************/ + +/* + * A feedback loop modeled after the PID controller. Currently supports the + * proportional (P) and the integral (I) terms; the derivative (D) term can be + * added if necessary. The setpoint (SP) is the desired position; the process + * variable (PV) is the measured position. The error is the difference between + * the SP and the PV. A positive error results in a positive control output + * correction, which, in our case, is to allow eviction. + * + * The P term is refaulted % of the current generation being evicted. The I + * term is the exponential moving average of refaulted % of previously evicted + * generations, using the smoothing factor 1/2. + * + * Our goal is to maintain proportional refaulted % across all tiers. + */ +struct ctrl_pos { + unsigned long refaulted; + unsigned long total; + int gain; +}; + +static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain, + struct ctrl_pos *pos) +{ + struct lrugen *lrugen = &lruvec->evictable; + int hist = lru_hist_from_seq(lrugen->min_seq[type]); + + pos->refaulted = lrugen->avg_refaulted[type][tier] + + atomic_long_read(&lrugen->refaulted[hist][type][tier]); + pos->total = lrugen->avg_total[type][tier] + + atomic_long_read(&lrugen->evicted[hist][type][tier]); + if (tier) + pos->total += lrugen->protected[hist][type][tier - 1]; + pos->gain = gain; +} + +static void reset_ctrl_pos(struct lruvec *lruvec, int gen, int type) +{ + int tier; + int hist = lru_hist_from_seq(gen); + struct lrugen *lrugen = &lruvec->evictable; + bool carryover = gen == lru_gen_from_seq(lrugen->min_seq[type]); + bool clear = carryover ? NR_HIST_GENS == 1 : NR_HIST_GENS > 1; + + if (!carryover && !clear) + return; + + for (tier = 0; tier < MAX_NR_TIERS; tier++) { + if (carryover) { + unsigned long sum; + + sum = lrugen->avg_refaulted[type][tier] + + atomic_long_read(&lrugen->refaulted[hist][type][tier]); + WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2); + + sum = lrugen->avg_total[type][tier] + + atomic_long_read(&lrugen->evicted[hist][type][tier]); + if (tier) + sum += lrugen->protected[hist][type][tier - 1]; + WRITE_ONCE(lrugen->avg_total[type][tier], sum / 2); + } + + if (clear) { + atomic_long_set(&lrugen->refaulted[hist][type][tier], 0); + atomic_long_set(&lrugen->evicted[hist][type][tier], 0); + if (tier) + WRITE_ONCE(lrugen->protected[hist][type][tier - 1], 0); + } + } +} + +static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv) +{ + /* + * Allow eviction if the PV has a limited number of refaulted pages or a + * lower refaulted % than the SP. + */ + return pv->refaulted < MIN_BATCH_SIZE || + pv->refaulted * max(sp->total, 1UL) * sp->gain <= + sp->refaulted * max(pv->total, 1UL) * pv->gain; +} + +/****************************************************************************** + * the aging + ******************************************************************************/ + +static int page_update_gen(struct page *page, int gen) +{ + unsigned long old_flags, new_flags; + + VM_BUG_ON(gen >= MAX_NR_GENS); + + do { + new_flags = old_flags = READ_ONCE(page->flags); + + if (!(new_flags & LRU_GEN_MASK)) { + new_flags |= BIT(PG_referenced); + continue; + } + + new_flags &= ~LRU_GEN_MASK; + new_flags |= (gen + 1UL) << LRU_GEN_PGOFF; + new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); + } while (new_flags != old_flags && + cmpxchg(&page->flags, old_flags, new_flags) != old_flags); + + return ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; +} + +static void page_inc_gen(struct page *page, struct lruvec *lruvec, bool reclaiming) +{ + int old_gen, new_gen; + unsigned long old_flags, new_flags; + int type = page_is_file_lru(page); + int zone = page_zonenum(page); + struct lrugen *lrugen = &lruvec->evictable; + + old_gen = lru_gen_from_seq(lrugen->min_seq[type]); + + do { + new_flags = old_flags = READ_ONCE(page->flags); + VM_BUG_ON_PAGE(!(new_flags & LRU_GEN_MASK), page); + + new_gen = ((new_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; + /* page_update_gen() has updated this page? */ + if (new_gen >= 0 && new_gen != old_gen) { + list_move(&page->lru, &lrugen->lists[new_gen][type][zone]); + return; + } + + new_gen = (old_gen + 1) % MAX_NR_GENS; + + new_flags &= ~LRU_GEN_MASK; + new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF; + new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); + /* for end_page_writeback() */ + if (reclaiming) + new_flags |= BIT(PG_reclaim); + } while (cmpxchg(&page->flags, old_flags, new_flags) != old_flags); + + lru_gen_update_size(page, lruvec, old_gen, new_gen); + if (reclaiming) + list_move(&page->lru, &lrugen->lists[new_gen][type][zone]); + else + list_move_tail(&page->lru, &lrugen->lists[new_gen][type][zone]); +} + +static void update_batch_size(struct page *page, int old_gen, int new_gen, + struct mm_walk_args *args) +{ + int type = page_is_file_lru(page); + int zone = page_zonenum(page); + int delta = thp_nr_pages(page); + + VM_BUG_ON(old_gen >= MAX_NR_GENS); + VM_BUG_ON(new_gen >= MAX_NR_GENS); + + args->batch_size++; + + args->nr_pages[old_gen][type][zone] -= delta; + args->nr_pages[new_gen][type][zone] += delta; +} + +static void reset_batch_size(struct lruvec *lruvec, struct mm_walk_args *args) +{ + int gen, type, zone; + struct lrugen *lrugen = &lruvec->evictable; + + args->batch_size = 0; + + for_each_gen_type_zone(gen, type, zone) { + enum lru_list lru = type * LRU_FILE; + int delta = args->nr_pages[gen][type][zone]; + + if (!delta) + continue; + + args->nr_pages[gen][type][zone] = 0; + WRITE_ONCE(lrugen->sizes[gen][type][zone], + lrugen->sizes[gen][type][zone] + delta); + + if (lru_gen_is_active(lruvec, gen)) + lru += LRU_ACTIVE; + update_lru_size(lruvec, lru, zone, delta); + } +} + +static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *walk) +{ + struct address_space *mapping; + struct vm_area_struct *vma = walk->vma; + struct mm_walk_args *args = walk->private; + + if (!vma_is_accessible(vma) || is_vm_hugetlb_page(vma) || + (vma->vm_flags & (VM_LOCKED | VM_SPECIAL | VM_SEQ_READ))) + return true; + + if (vma_is_anonymous(vma)) + return !args->swappiness; + + if (WARN_ON_ONCE(!vma->vm_file || !vma->vm_file->f_mapping)) + return true; + + mapping = vma->vm_file->f_mapping; + if (!mapping->a_ops->writepage) + return true; + + return (shmem_mapping(mapping) && !args->swappiness) || mapping_unevictable(mapping); +} + +/* + * Some userspace memory allocators create many single-page VMAs. So instead of + * returning back to the PGD table for each of such VMAs, we finish at least an + * entire PMD table and therefore avoid many zigzags. + */ +static bool get_next_vma(struct mm_walk *walk, unsigned long mask, unsigned long size, + unsigned long *start, unsigned long *end) +{ + unsigned long next = round_up(*end, size); + + VM_BUG_ON(mask & size); + VM_BUG_ON(*start >= *end); + VM_BUG_ON((next & mask) != (*start & mask)); + + while (walk->vma) { + if (next >= walk->vma->vm_end) { + walk->vma = walk->vma->vm_next; + continue; + } + + if ((next & mask) != (walk->vma->vm_start & mask)) + return false; + + if (should_skip_vma(walk->vma->vm_start, walk->vma->vm_end, walk)) { + walk->vma = walk->vma->vm_next; + continue; + } + + *start = max(next, walk->vma->vm_start); + next = (next | ~mask) + 1; + /* rounded-up boundaries can wrap to 0 */ + *end = next && next < walk->vma->vm_end ? next : walk->vma->vm_end; + + return true; + } + + return false; +} + +static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, + struct mm_walk *walk) +{ + int i; + pte_t *pte; + spinlock_t *ptl; + unsigned long addr; + int worth = 0; + struct mm_walk_args *args = walk->private; + int old_gen, new_gen = lru_gen_from_seq(args->max_seq); + + VM_BUG_ON(pmd_leaf(*pmd)); + + pte = pte_offset_map_lock(walk->mm, pmd, start & PMD_MASK, &ptl); + arch_enter_lazy_mmu_mode(); +restart: + for (i = pte_index(start), addr = start; addr != end; i++, addr += PAGE_SIZE) { + struct page *page; + unsigned long pfn = pte_pfn(pte[i]); + + args->mm_stats[MM_LEAF_TOTAL]++; + + if (!pte_present(pte[i]) || is_zero_pfn(pfn)) + continue; + + if (WARN_ON_ONCE(pte_devmap(pte[i]) || pte_special(pte[i]))) + continue; + + if (!pte_young(pte[i])) { + args->mm_stats[MM_LEAF_OLD]++; + continue; + } + + VM_BUG_ON(!pfn_valid(pfn)); + if (pfn < args->start_pfn || pfn >= args->end_pfn) + continue; + + page = compound_head(pfn_to_page(pfn)); + if (page_to_nid(page) != args->node_id) + continue; + + if (page_memcg_rcu(page) != args->memcg) + continue; + + VM_BUG_ON(addr < walk->vma->vm_start || addr >= walk->vma->vm_end); + if (!ptep_test_and_clear_young(walk->vma, addr, pte + i)) + continue; + + args->mm_stats[MM_LEAF_YOUNG]++; + + if (pte_dirty(pte[i]) && !PageDirty(page) && + !(PageAnon(page) && PageSwapBacked(page) && !PageSwapCache(page))) + set_page_dirty(page); + + old_gen = page_update_gen(page, new_gen); + if (old_gen >= 0 && old_gen != new_gen) + update_batch_size(page, old_gen, new_gen, args); + + worth++; + } + + if (i < PTRS_PER_PTE && get_next_vma(walk, PMD_MASK, PAGE_SIZE, &start, &end)) + goto restart; + + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(pte, ptl); + + return worth >= MIN_BATCH_SIZE / 2; +} + +/* + * We scan PMD entries in two passes. The first pass reaches to PTE tables and + * doesn't take the PMD lock. The second pass clears the accessed bit on PMD + * entries and needs to take the PMD lock. + */ +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) +static void walk_pmd_range_locked(pud_t *pud, unsigned long start, int offset, + struct vm_area_struct *vma, struct mm_walk *walk) +{ + int i; + pmd_t *pmd; + spinlock_t *ptl; + struct mm_walk_args *args = walk->private; + int old_gen, new_gen = lru_gen_from_seq(args->max_seq); + + VM_BUG_ON(pud_leaf(*pud)); + + start = (start & PUD_MASK) + offset * PMD_SIZE; + pmd = pmd_offset(pud, start); + ptl = pmd_lock(walk->mm, pmd); + arch_enter_lazy_mmu_mode(); + + for_each_set_bit(i, args->bitmap, MIN_BATCH_SIZE) { + struct page *page; + unsigned long pfn = pmd_pfn(pmd[i]); + unsigned long addr = start + i * PMD_SIZE; + + if (!pmd_present(pmd[i]) || is_huge_zero_pmd(pmd[i])) + continue; + + if (WARN_ON_ONCE(pmd_devmap(pmd[i]))) + continue; + + if (!pmd_trans_huge(pmd[i])) { + if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)) + pmdp_test_and_clear_young(vma, addr, pmd + i); + continue; + } + + VM_BUG_ON(!pfn_valid(pfn)); + if (pfn < args->start_pfn || pfn >= args->end_pfn) + continue; + + page = pfn_to_page(pfn); + VM_BUG_ON_PAGE(PageTail(page), page); + if (page_to_nid(page) != args->node_id) + continue; + + if (page_memcg_rcu(page) != args->memcg) + continue; + + VM_BUG_ON(addr < vma->vm_start || addr >= vma->vm_end); + if (!pmdp_test_and_clear_young(vma, addr, pmd + i)) + continue; + + args->mm_stats[MM_LEAF_YOUNG]++; + + if (pmd_dirty(pmd[i]) && !PageDirty(page) && + !(PageAnon(page) && PageSwapBacked(page) && !PageSwapCache(page))) + set_page_dirty(page); + + old_gen = page_update_gen(page, new_gen); + if (old_gen >= 0 && old_gen != new_gen) + update_batch_size(page, old_gen, new_gen, args); + } + + arch_leave_lazy_mmu_mode(); + spin_unlock(ptl); + + bitmap_zero(args->bitmap, MIN_BATCH_SIZE); +} +#else +static void walk_pmd_range_locked(pud_t *pud, unsigned long start, int offset, + struct vm_area_struct *vma, struct mm_walk *walk) +{ +} +#endif + +static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end, + struct mm_walk *walk) +{ + int i; + pmd_t *pmd; + unsigned long next; + unsigned long addr; + struct vm_area_struct *vma; + int offset = -1; + bool reset = false; + struct mm_walk_args *args = walk->private; + struct lruvec *lruvec = get_lruvec(args->node_id, args->memcg); + + VM_BUG_ON(pud_leaf(*pud)); + + pmd = pmd_offset(pud, start & PUD_MASK); +restart: + vma = walk->vma; + for (i = pmd_index(start), addr = start; addr != end; i++, addr = next) { + pmd_t val = pmd_read_atomic(pmd + i); + + /* for pmd_read_atomic() */ + barrier(); + + next = pmd_addr_end(addr, end); + + if (!pmd_present(val)) { + args->mm_stats[MM_LEAF_TOTAL]++; + continue; + } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (pmd_trans_huge(val)) { + unsigned long pfn = pmd_pfn(val); + + args->mm_stats[MM_LEAF_TOTAL]++; + + if (is_huge_zero_pmd(val)) + continue; + + if (!pmd_young(val)) { + args->mm_stats[MM_LEAF_OLD]++; + continue; + } + + if (pfn < args->start_pfn || pfn >= args->end_pfn) + continue; + + if (offset < 0) + offset = i; + else if (i - offset >= MIN_BATCH_SIZE) { + walk_pmd_range_locked(pud, start, offset, vma, walk); + offset = i; + } + __set_bit(i - offset, args->bitmap); + reset = true; + continue; + } +#endif + args->mm_stats[MM_NONLEAF_TOTAL]++; + +#ifdef CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG + if (!pmd_young(val)) + continue; + + if (offset < 0) + offset = i; + else if (i - offset >= MIN_BATCH_SIZE) { + walk_pmd_range_locked(pud, start, offset, vma, walk); + offset = i; + reset = false; + } + __set_bit(i - offset, args->bitmap); +#endif + if (args->use_filter && !test_bloom_filter(lruvec, args->max_seq, pmd + i)) + continue; + + args->mm_stats[MM_NONLEAF_PREV]++; + + if (!walk_pte_range(&val, addr, next, walk)) + continue; + + args->mm_stats[MM_NONLEAF_CUR]++; + + set_bloom_filter(lruvec, args->max_seq + 1, pmd + i); + } + + if (reset) { + walk_pmd_range_locked(pud, start, offset, vma, walk); + offset = -1; + reset = false; + } + + if (i < PTRS_PER_PMD && get_next_vma(walk, PUD_MASK, PMD_SIZE, &start, &end)) + goto restart; + + if (offset >= 0) + walk_pmd_range_locked(pud, start, offset, vma, walk); +} + +static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end, + struct mm_walk *walk) +{ + int i; + pud_t *pud; + unsigned long addr; + unsigned long next; + struct mm_walk_args *args = walk->private; + + VM_BUG_ON(p4d_leaf(*p4d)); + + pud = pud_offset(p4d, start & P4D_MASK); +restart: + for (i = pud_index(start), addr = start; addr != end; i++, addr = next) { + pud_t val = READ_ONCE(pud[i]); + + next = pud_addr_end(addr, end); + + if (!pud_present(val) || WARN_ON_ONCE(pud_leaf(val))) + continue; + + walk_pmd_range(&val, addr, next, walk); + + if (args->batch_size >= MAX_BATCH_SIZE) { + end = (addr | ~PUD_MASK) + 1; + goto done; + } + } + + if (i < PTRS_PER_PUD && get_next_vma(walk, P4D_MASK, PUD_SIZE, &start, &end)) + goto restart; + + end = round_up(end, P4D_SIZE); +done: + /* rounded-up boundaries can wrap to 0 */ + args->next_addr = end && walk->vma ? max(end, walk->vma->vm_start) : 0; + + return -EAGAIN; +} + +static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct mm_walk_args *args) +{ + static const struct mm_walk_ops mm_walk_ops = { + .test_walk = should_skip_vma, + .p4d_entry = walk_pud_range, + }; + + int err; + + args->next_addr = FIRST_USER_ADDRESS; + + do { + unsigned long start = args->next_addr; + unsigned long end = mm->highest_vm_end; + + err = -EBUSY; + + rcu_read_lock(); +#ifdef CONFIG_MEMCG + if (args->memcg && atomic_read(&args->memcg->moving_account)) + goto contended; +#endif + if (!mmap_read_trylock(mm)) + goto contended; + + err = walk_page_range(mm, start, end, &mm_walk_ops, args); + + mmap_read_unlock(mm); + + if (args->batch_size) { + spin_lock_irq(&lruvec->lru_lock); + reset_batch_size(lruvec, args); + spin_unlock_irq(&lruvec->lru_lock); + } +contended: + rcu_read_unlock(); + + cond_resched(); + } while (err == -EAGAIN && args->next_addr && !mm_is_oom_victim(mm)); +} + +static struct mm_walk_args *alloc_mm_walk_args(void) +{ + if (!current->reclaim_state || !current->reclaim_state->mm_walk_args) + return kvzalloc(sizeof(struct mm_walk_args), GFP_KERNEL); + + return current->reclaim_state->mm_walk_args; +} + +static void free_mm_walk_args(struct mm_walk_args *args) +{ + if (!current->reclaim_state || !current->reclaim_state->mm_walk_args) + kvfree(args); +} + +static bool inc_min_seq(struct lruvec *lruvec, int type) +{ + int gen, zone; + int remaining = MAX_BATCH_SIZE; + struct lrugen *lrugen = &lruvec->evictable; + + VM_BUG_ON(!seq_is_valid(lruvec)); + + if (get_nr_gens(lruvec, type) != MAX_NR_GENS) + return true; + + gen = lru_gen_from_seq(lrugen->min_seq[type]); + + for (zone = 0; zone < MAX_NR_ZONES; zone++) { + struct list_head *head = &lrugen->lists[gen][type][zone]; + + while (!list_empty(head)) { + struct page *page = lru_to_page(head); + + VM_BUG_ON_PAGE(PageTail(page), page); + VM_BUG_ON_PAGE(PageUnevictable(page), page); + VM_BUG_ON_PAGE(PageActive(page), page); + VM_BUG_ON_PAGE(page_is_file_lru(page) != type, page); + VM_BUG_ON_PAGE(page_zonenum(page) != zone, page); + + prefetchw_prev_lru_page(page, head, flags); + + page_inc_gen(page, lruvec, false); + + if (!--remaining) + return false; + } + } + + reset_ctrl_pos(lruvec, gen, type); + WRITE_ONCE(lrugen->min_seq[type], lrugen->min_seq[type] + 1); + + return true; +} + +static bool try_to_inc_min_seq(struct lruvec *lruvec, int swappiness) +{ + int gen, type, zone; + bool success = false; + struct lrugen *lrugen = &lruvec->evictable; + DEFINE_MIN_SEQ(lruvec); + + VM_BUG_ON(!seq_is_valid(lruvec)); + + for (type = 0; type < ANON_AND_FILE; type++) { + while (lrugen->max_seq - min_seq[type] >= MIN_NR_GENS) { + gen = lru_gen_from_seq(min_seq[type]); + + for (zone = 0; zone < MAX_NR_ZONES; zone++) { + if (!list_empty(&lrugen->lists[gen][type][zone])) + goto next; + } + + min_seq[type]++; + } +next: + ; + } + + min_seq[0] = min(min_seq[0], min_seq[1]); + if (swappiness) + min_seq[1] = max(min_seq[0], lrugen->min_seq[1]); + + for (type = 0; type < ANON_AND_FILE; type++) { + if (min_seq[type] == lrugen->min_seq[type]) + continue; + + gen = lru_gen_from_seq(lrugen->min_seq[type]); + reset_ctrl_pos(lruvec, gen, type); + WRITE_ONCE(lrugen->min_seq[type], min_seq[type]); + success = true; + } + + return success; +} + +static void inc_max_seq(struct lruvec *lruvec, unsigned long max_seq) +{ + int gen, type, zone; + struct lrugen *lrugen = &lruvec->evictable; + + spin_lock_irq(&lruvec->lru_lock); + + VM_BUG_ON(!seq_is_valid(lruvec)); + + if (max_seq != lrugen->max_seq) + goto unlock; + + if (!try_to_inc_min_seq(lruvec, true)) { + for (type = ANON_AND_FILE - 1; type >= 0; type--) { + while (!inc_min_seq(lruvec, type)) { + spin_unlock_irq(&lruvec->lru_lock); + cond_resched(); + spin_lock_irq(&lruvec->lru_lock); + } + } + } + + gen = lru_gen_from_seq(lrugen->max_seq - 1); + for (type = 0; type < ANON_AND_FILE; type++) { + for (zone = 0; zone < MAX_NR_ZONES; zone++) { + enum lru_list lru = type * LRU_FILE; + long delta = lrugen->sizes[gen][type][zone]; + + if (!delta) + continue; + + WARN_ON_ONCE(delta != (int)delta); + + update_lru_size(lruvec, lru, zone, delta); + update_lru_size(lruvec, lru + LRU_ACTIVE, zone, -delta); + } + } + + gen = lru_gen_from_seq(lrugen->max_seq + 1); + for (type = 0; type < ANON_AND_FILE; type++) { + for (zone = 0; zone < MAX_NR_ZONES; zone++) { + enum lru_list lru = type * LRU_FILE; + long delta = lrugen->sizes[gen][type][zone]; + + if (!delta) + continue; + + WARN_ON_ONCE(delta != (int)delta); + + update_lru_size(lruvec, lru, zone, -delta); + update_lru_size(lruvec, lru + LRU_ACTIVE, zone, delta); + } + } + + for (type = 0; type < ANON_AND_FILE; type++) + reset_ctrl_pos(lruvec, gen, type); + + WRITE_ONCE(lrugen->timestamps[gen], jiffies); + /* make sure all preceding modifications appear first */ + smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1); +unlock: + spin_unlock_irq(&lruvec->lru_lock); +} + +/* Main function used by the foreground, the background and the user-triggered aging. */ +static bool try_to_inc_max_seq(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + unsigned long max_seq, bool use_filter) +{ + bool last; + struct mm_walk_args *args; + struct mm_struct *mm = NULL; + struct lrugen *lrugen = &lruvec->evictable; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + int nid = pgdat->node_id; + + VM_BUG_ON(max_seq > READ_ONCE(lrugen->max_seq)); + + /* + * If we are not from run_aging() and clearing the accessed bit may + * trigger page faults, then don't proceed to clearing all accessed + * PTEs. Instead, fallback to lru_gen_look_around(), which only clears a + * handful of accessed PTEs. This is less efficient but causes fewer + * page faults on CPUs that don't have the capability. + */ + if ((current->flags & PF_MEMALLOC) && !arch_has_hw_pte_young(false)) { + inc_max_seq(lruvec, max_seq); + return true; + } + + args = alloc_mm_walk_args(); + if (!args) + return false; + + args->memcg = memcg; + args->max_seq = max_seq; + args->start_pfn = pgdat->node_start_pfn; + args->end_pfn = pgdat_end_pfn(pgdat); + args->node_id = nid; + args->swappiness = swappiness; + args->use_filter = use_filter; + + do { + last = get_next_mm(lruvec, args, &mm); + if (mm) + walk_mm(lruvec, mm, args); + + cond_resched(); + } while (mm); + + free_mm_walk_args(args); + + if (!last) { + /* don't wait unless we may have trouble reclaiming */ + if (!current_is_kswapd() && sc->priority < DEF_PRIORITY - 2) + wait_event_killable(lruvec->mm_walk.wait, + max_seq < READ_ONCE(lrugen->max_seq)); + + return max_seq < READ_ONCE(lrugen->max_seq); + } + + VM_BUG_ON(max_seq != READ_ONCE(lrugen->max_seq)); + + inc_max_seq(lruvec, max_seq); + /* either we see any waiters or they will see updated max_seq */ + if (wq_has_sleeper(&lruvec->mm_walk.wait)) + wake_up_all(&lruvec->mm_walk.wait); + + wakeup_flusher_threads(WB_REASON_VMSCAN); + + return true; +} + +static long get_nr_evictable(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + unsigned long max_seq, unsigned long *min_seq, bool *low) +{ + int gen, type, zone; + long max = 0; + long min = 0; + struct lrugen *lrugen = &lruvec->evictable; + + for (type = !swappiness; type < ANON_AND_FILE; type++) { + unsigned long seq; + + for (seq = min_seq[type]; seq <= max_seq; seq++) { + long size = 0; + + gen = lru_gen_from_seq(seq); + + for (zone = 0; zone <= sc->reclaim_idx; zone++) + size += READ_ONCE(lrugen->sizes[gen][type][zone]); + + max += size; + if (type && max_seq - seq >= MIN_NR_GENS) + min += size; + } + } + + *low = max_seq - min_seq[1] <= MIN_NR_GENS && min < MIN_BATCH_SIZE; + + return max > 0 ? max : 0; +} + +static bool age_lruvec(struct lruvec *lruvec, struct scan_control *sc, + unsigned long min_ttl) +{ + bool low; + long nr_to_scan; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + int swappiness = get_swappiness(memcg); + DEFINE_MAX_SEQ(lruvec); + DEFINE_MIN_SEQ(lruvec); + + if (mem_cgroup_below_min(memcg)) + return false; + + if (min_ttl) { + int gen = lru_gen_from_seq(min_seq[1]); + unsigned long birth = READ_ONCE(lruvec->evictable.timestamps[gen]); + + if (time_is_after_jiffies(birth + min_ttl)) + return false; + } + + nr_to_scan = get_nr_evictable(lruvec, sc, swappiness, max_seq, min_seq, &low); + if (!nr_to_scan) + return false; + + nr_to_scan >>= sc->priority; + + if (!mem_cgroup_online(memcg)) + nr_to_scan++; + + if (nr_to_scan && low && (!mem_cgroup_below_low(memcg) || sc->memcg_low_reclaim)) + try_to_inc_max_seq(lruvec, sc, swappiness, max_seq, true); + + return true; +} + +/* Protect the working set accessed within the last N milliseconds. */ +static unsigned long lru_gen_min_ttl __read_mostly; + +static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) +{ + struct mem_cgroup *memcg; + bool success = false; + unsigned long min_ttl = READ_ONCE(lru_gen_min_ttl); + + VM_BUG_ON(!current_is_kswapd()); + + if (!sc->force_deactivate) { + sc->force_deactivate = 1; + return; + } + + current->reclaim_state->mm_walk_args = &pgdat->mm_walk_args; + + memcg = mem_cgroup_iter(NULL, NULL, NULL); + do { + struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); + + if (age_lruvec(lruvec, sc, min_ttl)) + success = true; + + cond_resched(); + } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); + + if (!success && mutex_trylock(&oom_lock)) { + struct oom_control oc = { + .gfp_mask = sc->gfp_mask, + .order = sc->order, + }; + + /* to avoid overkilling */ + if (!oom_reaping_in_progress()) + out_of_memory(&oc); + + mutex_unlock(&oom_lock); + } + + current->reclaim_state->mm_walk_args = NULL; +} + +/* Scan the vicinity of an accessed PTE when shrink_page_list() uses the rmap. */ +void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) +{ + int i; + pte_t *pte; + struct page *page; + int old_gen, new_gen; + unsigned long start; + unsigned long end; + unsigned long addr; + struct mm_walk_args *args; + int worth = 0; + struct mem_cgroup *memcg = page_memcg(pvmw->page); + struct pglist_data *pgdat = page_pgdat(pvmw->page); + struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); + DEFINE_MAX_SEQ(lruvec); + + lockdep_assert_held(pvmw->ptl); + VM_BUG_ON_PAGE(PageLRU(pvmw->page), pvmw->page); + + args = current->reclaim_state ? current->reclaim_state->mm_walk_args : NULL; + if (!args) + return; + + start = max(pvmw->address & PMD_MASK, pvmw->vma->vm_start); + end = pmd_addr_end(pvmw->address, pvmw->vma->vm_end); + + if (end - start > MIN_BATCH_SIZE * PAGE_SIZE) { + if (pvmw->address - start < MIN_BATCH_SIZE * PAGE_SIZE / 2) + end = start + MIN_BATCH_SIZE * PAGE_SIZE; + else if (end - pvmw->address < MIN_BATCH_SIZE * PAGE_SIZE / 2) + start = end - MIN_BATCH_SIZE * PAGE_SIZE; + else { + start = pvmw->address - MIN_BATCH_SIZE * PAGE_SIZE / 2; + end = pvmw->address + MIN_BATCH_SIZE * PAGE_SIZE / 2; + } + } + + pte = pvmw->pte - (pvmw->address - start) / PAGE_SIZE; + new_gen = lru_gen_from_seq(max_seq); + + lock_page_memcg(pvmw->page); + arch_enter_lazy_mmu_mode(); + + for (i = 0, addr = start; addr != end; i++, addr += PAGE_SIZE) { + unsigned long pfn = pte_pfn(pte[i]); + + if (!pte_present(pte[i]) || is_zero_pfn(pfn)) + continue; + + if (WARN_ON_ONCE(pte_devmap(pte[i]) || pte_special(pte[i]))) + continue; + + VM_BUG_ON(!pfn_valid(pfn)); + if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) + continue; + + worth++; + + if (!pte_young(pte[i])) + continue; + + page = compound_head(pfn_to_page(pfn)); + if (page_to_nid(page) != pgdat->node_id) + continue; + + if (page_memcg_rcu(page) != memcg) + continue; + + VM_BUG_ON(addr < pvmw->vma->vm_start || addr >= pvmw->vma->vm_end); + if (!ptep_test_and_clear_young(pvmw->vma, addr, pte + i)) + continue; + + if (pte_dirty(pte[i]) && !PageDirty(page) && + !(PageAnon(page) && PageSwapBacked(page) && !PageSwapCache(page))) + __set_bit(i, args->bitmap); + + old_gen = page_update_gen(page, new_gen); + if (old_gen >= 0 && old_gen != new_gen) + update_batch_size(page, old_gen, new_gen, args); + } + + arch_leave_lazy_mmu_mode(); + unlock_page_memcg(pvmw->page); + + if (worth >= MIN_BATCH_SIZE / 2) + set_bloom_filter(lruvec, max_seq, pvmw->pmd); + + for_each_set_bit(i, args->bitmap, MIN_BATCH_SIZE) + set_page_dirty(pte_page(pte[i])); + + bitmap_zero(args->bitmap, MIN_BATCH_SIZE); +} + +/****************************************************************************** + * the eviction + ******************************************************************************/ + +static bool sort_page(struct page *page, struct lruvec *lruvec, int tier_idx) +{ + bool success; + int gen = page_lru_gen(page); + int type = page_is_file_lru(page); + int zone = page_zonenum(page); + int tier = page_lru_tier(page); + int delta = thp_nr_pages(page); + struct lrugen *lrugen = &lruvec->evictable; + + VM_BUG_ON_PAGE(gen >= MAX_NR_GENS, page); + + /* an mlocked page? */ + if (!page_evictable(page)) { + success = lru_gen_del_page(page, lruvec, true); + VM_BUG_ON_PAGE(!success, page); + SetPageUnevictable(page); + add_page_to_lru_list(page, lruvec); + __count_vm_events(UNEVICTABLE_PGCULLED, delta); + return true; + } + + /* a lazy-free page that has been written into? */ + if (type && PageDirty(page) && PageAnon(page)) { + success = lru_gen_del_page(page, lruvec, true); + VM_BUG_ON_PAGE(!success, page); + SetPageSwapBacked(page); + add_page_to_lru_list_tail(page, lruvec); + return true; + } + + /* page_update_gen() has updated this page? */ + if (gen != lru_gen_from_seq(lrugen->min_seq[type])) { + list_move(&page->lru, &lrugen->lists[gen][type][zone]); + return true; + } + + /* protect this page if its tier has a higher refaulted % */ + if (tier > tier_idx) { + int hist = lru_hist_from_seq(gen); + + page_inc_gen(page, lruvec, false); + WRITE_ONCE(lrugen->protected[hist][type][tier - 1], + lrugen->protected[hist][type][tier - 1] + delta); + __mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + type, delta); + return true; + } + + /* mark this page for reclaim if it's pending writeback */ + if (PageWriteback(page) || (type && PageDirty(page))) { + page_inc_gen(page, lruvec, true); + return true; + } + + return false; +} + +static bool isolate_page(struct page *page, struct lruvec *lruvec, struct scan_control *sc) +{ + bool success; + + if (!sc->may_unmap && page_mapped(page)) + return false; + + if (!(sc->may_writepage && (sc->gfp_mask & __GFP_IO)) && + (PageDirty(page) || (PageAnon(page) && !PageSwapCache(page)))) + return false; + + if (!get_page_unless_zero(page)) + return false; + + if (!TestClearPageLRU(page)) { + put_page(page); + return false; + } + + success = lru_gen_del_page(page, lruvec, true); + VM_BUG_ON_PAGE(!success, page); + + return true; +} + +static int scan_pages(struct lruvec *lruvec, struct scan_control *sc, + int type, int tier, struct list_head *list) +{ + int gen, zone; + enum vm_event_item item; + int sorted = 0; + int scanned = 0; + int isolated = 0; + int remaining = MAX_BATCH_SIZE; + struct lrugen *lrugen = &lruvec->evictable; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + + VM_BUG_ON(!list_empty(list)); + + if (get_nr_gens(lruvec, type) == MIN_NR_GENS) + return 0; + + gen = lru_gen_from_seq(lrugen->min_seq[type]); + + for (zone = sc->reclaim_idx; zone >= 0; zone--) { + LIST_HEAD(moved); + int skipped = 0; + struct list_head *head = &lrugen->lists[gen][type][zone]; + + while (!list_empty(head)) { + struct page *page = lru_to_page(head); + int delta = thp_nr_pages(page); + + VM_BUG_ON_PAGE(PageTail(page), page); + VM_BUG_ON_PAGE(PageUnevictable(page), page); + VM_BUG_ON_PAGE(PageActive(page), page); + VM_BUG_ON_PAGE(page_is_file_lru(page) != type, page); + VM_BUG_ON_PAGE(page_zonenum(page) != zone, page); + + prefetchw_prev_lru_page(page, head, flags); + + scanned += delta; + + if (sort_page(page, lruvec, tier)) + sorted += delta; + else if (isolate_page(page, lruvec, sc)) { + list_add(&page->lru, list); + isolated += delta; + } else { + list_move(&page->lru, &moved); + skipped += delta; + } + + if (!--remaining || max(isolated, skipped) >= MIN_BATCH_SIZE) + break; + } + + if (skipped) { + list_splice(&moved, head); + __count_zid_vm_events(PGSCAN_SKIP, zone, skipped); + } + + if (!remaining || isolated >= MIN_BATCH_SIZE) + break; + } + + item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT; + if (!cgroup_reclaim(sc)) { + __count_vm_events(item, isolated); + __count_vm_events(PGREFILL, sorted); + } + __count_memcg_events(memcg, item, isolated); + __count_memcg_events(memcg, PGREFILL, sorted); + __count_vm_events(PGSCAN_ANON + type, isolated); + + /* + * We may have trouble finding eligible pages due to reclaim_idx, + * may_unmap and may_writepage. Check `remaining` to make sure we won't + * be stuck if we aren't making enough progress. + */ + return isolated || !remaining ? scanned : 0; +} + +static int get_tier_idx(struct lruvec *lruvec, int type) +{ + int tier; + struct ctrl_pos sp, pv; + + /* + * Ideally we don't want to evict upper tiers that have higher refaulted + * %. However, we need to leave a margin for the fluctuation in + * refaulted %. So we use a larger gain factor to make sure upper tiers + * are indeed more active. We choose 2 because the lowest upper tier + * would have twice of refaulted % of the base tier, according to their + * numbers of accesses. + */ + read_ctrl_pos(lruvec, type, 0, 1, &sp); + for (tier = 1; tier < MAX_NR_TIERS; tier++) { + read_ctrl_pos(lruvec, type, tier, 2, &pv); + if (!positive_ctrl_err(&sp, &pv)) + break; + } + + return tier - 1; +} + +static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx) +{ + int type, tier; + struct ctrl_pos sp, pv; + int gain[ANON_AND_FILE] = { swappiness, 200 - swappiness }; + + /* + * Compare refaulted % between the base tiers of anon and file to + * determine which type to evict. Also need to compare refaulted % of + * the upper tiers of the selected type with that of the base tier of + * the other type to determine which tier of the selected type to evict. + */ + read_ctrl_pos(lruvec, 0, 0, gain[0], &sp); + read_ctrl_pos(lruvec, 1, 0, gain[1], &pv); + type = positive_ctrl_err(&sp, &pv); + + read_ctrl_pos(lruvec, !type, 0, gain[!type], &sp); + for (tier = 1; tier < MAX_NR_TIERS; tier++) { + read_ctrl_pos(lruvec, type, tier, gain[type], &pv); + if (!positive_ctrl_err(&sp, &pv)) + break; + } + + *tier_idx = tier - 1; + + return type; +} + +static int isolate_pages(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + int *type_scanned, struct list_head *list) +{ + int i; + int type; + int scanned; + int tier = -1; + DEFINE_MIN_SEQ(lruvec); + + VM_BUG_ON(!seq_is_valid(lruvec)); + + /* + * Try to select a type based on generations and swappiness, and if that + * fails, fall back to get_type_to_scan(). When anon and file are both + * available from the same generation, swappiness 200 is interpreted as + * anon first and swappiness 1 is interpreted as file first. + */ + if (!swappiness) + type = 1; + else if (min_seq[0] < min_seq[1]) + type = 0; + else if (swappiness == 1) + type = 1; + else if (swappiness == 200) + type = 0; + else + type = get_type_to_scan(lruvec, swappiness, &tier); + + for (i = !swappiness; i < ANON_AND_FILE; i++) { + if (tier < 0) + tier = get_tier_idx(lruvec, type); + + scanned = scan_pages(lruvec, sc, type, tier, list); + if (scanned) + break; + + type = !type; + tier = -1; + } + + *type_scanned = type; + + return scanned; +} + +/* Main function used by the foreground, the background and the user-triggered eviction. */ +static int evict_pages(struct lruvec *lruvec, struct scan_control *sc, int swappiness) +{ + int type; + int scanned; + int reclaimed; + LIST_HEAD(list); + struct page *page; + enum vm_event_item item; + struct reclaim_stat stat; + struct mm_walk_args *args; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + spin_lock_irq(&lruvec->lru_lock); + + scanned = isolate_pages(lruvec, sc, swappiness, &type, &list); + + if (try_to_inc_min_seq(lruvec, swappiness)) + scanned++; + + if (get_nr_gens(lruvec, 1) == MIN_NR_GENS) + scanned = 0; + + spin_unlock_irq(&lruvec->lru_lock); + + if (list_empty(&list)) + return scanned; + + reclaimed = shrink_page_list(&list, pgdat, sc, &stat, false); + /* + * We need to prevent rejected pages from being added back to the same + * lists they were isolated from. Otherwise we may risk looping on them + * forever. + */ + list_for_each_entry(page, &list, lru) { + if (!PageReclaim(page) || !(PageDirty(page) || PageWriteback(page))) + SetPageActive(page); + + ClearPageReferenced(page); + ClearPageWorkingset(page); + } + + spin_lock_irq(&lruvec->lru_lock); + + move_pages_to_lru(lruvec, &list); + + args = current->reclaim_state ? current->reclaim_state->mm_walk_args : NULL; + if (args && args->batch_size) + reset_batch_size(lruvec, args); + + item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT; + if (!cgroup_reclaim(sc)) + __count_vm_events(item, reclaimed); + __count_memcg_events(memcg, item, reclaimed); + __count_vm_events(PGSTEAL_ANON + type, reclaimed); + + spin_unlock_irq(&lruvec->lru_lock); + + mem_cgroup_uncharge_list(&list); + free_unref_page_list(&list); + + sc->nr_reclaimed += reclaimed; + + return scanned; +} + +static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, int swappiness) +{ + bool low; + long nr_to_scan; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + int priority = sc->priority; + DEFINE_MAX_SEQ(lruvec); + DEFINE_MIN_SEQ(lruvec); + + if (mem_cgroup_below_min(memcg) || + (mem_cgroup_below_low(memcg) && !sc->memcg_low_reclaim)) + return 0; + + if (sc->nr_reclaimed >= sc->nr_to_reclaim) { + priority = DEF_PRIORITY; + sc->force_deactivate = 0; + } + + nr_to_scan = get_nr_evictable(lruvec, sc, swappiness, max_seq, min_seq, &low); + if (!nr_to_scan) + return 0; + + nr_to_scan >>= priority; + + if (!mem_cgroup_online(memcg)) + nr_to_scan++; + + if (!nr_to_scan) + return 0; + + if (current_is_kswapd()) { + /* leave the work to lru_gen_age_node() */ + if (max_seq - min_seq[1] < MIN_NR_GENS) + return 0; + + if (!low) + sc->force_deactivate = 0; + + return nr_to_scan; + } + + if (max_seq - min_seq[1] >= MIN_NR_GENS) + return nr_to_scan; + + /* move onto slab and other memcgs if we haven't tried them all */ + if (!sc->force_deactivate) { + sc->skipped_deactivate = 1; + return 0; + } + + return try_to_inc_max_seq(lruvec, sc, swappiness, max_seq, true) ? nr_to_scan : 0; +} + +static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +{ + struct blk_plug plug; + long scanned = 0; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + lru_add_drain(); + + if (current_is_kswapd()) + current->reclaim_state->mm_walk_args = &pgdat->mm_walk_args; + + blk_start_plug(&plug); + + while (true) { + int delta; + int swappiness; + long nr_to_scan; + + if (sc->may_swap) + swappiness = get_swappiness(memcg); + else if (!cgroup_reclaim(sc) && get_swappiness(memcg)) + swappiness = 1; + else + swappiness = 0; + + nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness); + if (!nr_to_scan) + break; + + delta = evict_pages(lruvec, sc, swappiness); + if (!delta) + break; + + scanned += delta; + if (scanned >= nr_to_scan) + break; + + cond_resched(); + } + + blk_finish_plug(&plug); + + if (current_is_kswapd()) + current->reclaim_state->mm_walk_args = NULL; +} + +/****************************************************************************** + * state change + ******************************************************************************/ + +#ifdef CONFIG_LRU_GEN_ENABLED +DEFINE_STATIC_KEY_TRUE(lru_gen_static_key); +#else +DEFINE_STATIC_KEY_FALSE(lru_gen_static_key); +#endif + +static int lru_gen_nr_swapfiles; + +static bool __maybe_unused state_is_valid(struct lruvec *lruvec) +{ + int gen, type, zone; + enum lru_list lru; + struct lrugen *lrugen = &lruvec->evictable; + + for_each_evictable_lru(lru) { + type = is_file_lru(lru); + + if (lrugen->enabled[type] && !list_empty(&lruvec->lists[lru])) + return false; + } + + for_each_gen_type_zone(gen, type, zone) { + if (!lrugen->enabled[type] && !list_empty(&lrugen->lists[gen][type][zone])) + return false; + + /* unlikely but not a bug when reset_batch_size() is pending */ + VM_WARN_ON(!lrugen->enabled[type] && lrugen->sizes[gen][type][zone]); + } + + return true; +} + +static bool fill_lists(struct lruvec *lruvec) +{ + enum lru_list lru; + int remaining = MAX_BATCH_SIZE; + + for_each_evictable_lru(lru) { + int type = is_file_lru(lru); + bool active = is_active_lru(lru); + struct list_head *head = &lruvec->lists[lru]; + + if (!lruvec->evictable.enabled[type]) + continue; + + while (!list_empty(head)) { + bool success; + struct page *page = lru_to_page(head); + + VM_BUG_ON_PAGE(PageTail(page), page); + VM_BUG_ON_PAGE(PageUnevictable(page), page); + VM_BUG_ON_PAGE(PageActive(page) != active, page); + VM_BUG_ON_PAGE(page_is_file_lru(page) != type, page); + VM_BUG_ON_PAGE(page_lru_gen(page) < MAX_NR_GENS, page); + + prefetchw_prev_lru_page(page, head, flags); + + del_page_from_lru_list(page, lruvec); + success = lru_gen_add_page(page, lruvec, false); + VM_BUG_ON(!success); + + if (!--remaining) + return false; + } + } + + return true; +} + +static bool drain_lists(struct lruvec *lruvec) +{ + int gen, type, zone; + int remaining = MAX_BATCH_SIZE; + + for_each_gen_type_zone(gen, type, zone) { + struct list_head *head = &lruvec->evictable.lists[gen][type][zone]; + + if (lruvec->evictable.enabled[type]) + continue; + + while (!list_empty(head)) { + bool success; + struct page *page = lru_to_page(head); + + VM_BUG_ON_PAGE(PageTail(page), page); + VM_BUG_ON_PAGE(PageUnevictable(page), page); + VM_BUG_ON_PAGE(PageActive(page), page); + VM_BUG_ON_PAGE(page_is_file_lru(page) != type, page); + VM_BUG_ON_PAGE(page_zonenum(page) != zone, page); + + prefetchw_prev_lru_page(page, head, flags); + + success = lru_gen_del_page(page, lruvec, false); + VM_BUG_ON(!success); + add_page_to_lru_list(page, lruvec); + + if (!--remaining) + return false; + } + } + + return true; +} + +/* + * For file page tracking, we enable/disable it according to the main switch. + * For anon page tracking, we only enabled it when the main switch is on and + * there is at least one swapfile; we disable it when there are no swapfiles + * regardless of the value of the main switch. Otherwise, we will eventually + * reach the max size of the sliding window and have to call inc_min_seq(). + */ +void lru_gen_change_state(bool enable, bool main, bool swap) +{ + static DEFINE_MUTEX(state_mutex); + + struct mem_cgroup *memcg; + + mem_hotplug_begin(); + cgroup_lock(); + mutex_lock(&state_mutex); + + if (swap) { + if (enable) + swap = !lru_gen_nr_swapfiles++; + else + swap = !--lru_gen_nr_swapfiles; + } + + if (main && enable != lru_gen_enabled()) { + if (enable) + static_branch_enable(&lru_gen_static_key); + else + static_branch_disable(&lru_gen_static_key); + } else if (!swap || !lru_gen_enabled()) + goto unlock; + + memcg = mem_cgroup_iter(NULL, NULL, NULL); + do { + int nid; + + for_each_node(nid) { + struct lruvec *lruvec = get_lruvec(nid, memcg); + + if (!lruvec) + continue; + + spin_lock_irq(&lruvec->lru_lock); + + VM_BUG_ON(!seq_is_valid(lruvec)); + VM_BUG_ON(!state_is_valid(lruvec)); + + lruvec->evictable.enabled[0] = lru_gen_enabled() && lru_gen_nr_swapfiles; + lruvec->evictable.enabled[1] = lru_gen_enabled(); + + while (!(enable ? fill_lists(lruvec) : drain_lists(lruvec))) { + spin_unlock_irq(&lruvec->lru_lock); + cond_resched(); + spin_lock_irq(&lruvec->lru_lock); + } + + spin_unlock_irq(&lruvec->lru_lock); + } + + cond_resched(); + } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); +unlock: + mutex_unlock(&state_mutex); + cgroup_unlock(); + mem_hotplug_done(); +} + +/****************************************************************************** + * sysfs interface + ******************************************************************************/ + +static ssize_t show_min_ttl(struct kobject *kobj, struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%u\n", jiffies_to_msecs(READ_ONCE(lru_gen_min_ttl))); +} + +static ssize_t store_min_ttl(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t len) +{ + unsigned int msecs; + + if (kstrtouint(buf, 10, &msecs)) + return -EINVAL; + + WRITE_ONCE(lru_gen_min_ttl, msecs_to_jiffies(msecs)); + + return len; +} + +static struct kobj_attribute lru_gen_min_ttl_attr = __ATTR( + min_ttl_ms, 0644, show_min_ttl, store_min_ttl +); + +static ssize_t show_enable(struct kobject *kobj, struct kobj_attribute *attr, char *buf) +{ + return snprintf(buf, PAGE_SIZE, "%d\n", lru_gen_enabled()); +} + +static ssize_t store_enable(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t len) +{ + bool enable; + + if (kstrtobool(buf, &enable)) + return -EINVAL; + + lru_gen_change_state(enable, true, false); + + return len; +} + +static struct kobj_attribute lru_gen_enabled_attr = __ATTR( + enabled, 0644, show_enable, store_enable +); + +static struct attribute *lru_gen_attrs[] = { + &lru_gen_min_ttl_attr.attr, + &lru_gen_enabled_attr.attr, + NULL +}; + +static struct attribute_group lru_gen_attr_group = { + .name = "lru_gen", + .attrs = lru_gen_attrs, +}; + +/****************************************************************************** + * debugfs interface + ******************************************************************************/ + +static void *lru_gen_seq_start(struct seq_file *m, loff_t *pos) +{ + struct mem_cgroup *memcg; + loff_t nr_to_skip = *pos; + + m->private = kvmalloc(PATH_MAX, GFP_KERNEL); + if (!m->private) + return ERR_PTR(-ENOMEM); + + memcg = mem_cgroup_iter(NULL, NULL, NULL); + do { + int nid; + + for_each_node_state(nid, N_MEMORY) { + if (!nr_to_skip--) + return get_lruvec(nid, memcg); + } + } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); + + return NULL; +} + +static void lru_gen_seq_stop(struct seq_file *m, void *v) +{ + if (!IS_ERR_OR_NULL(v)) + mem_cgroup_iter_break(NULL, lruvec_memcg(v)); + + kvfree(m->private); + m->private = NULL; +} + +static void *lru_gen_seq_next(struct seq_file *m, void *v, loff_t *pos) +{ + int nid = lruvec_pgdat(v)->node_id; + struct mem_cgroup *memcg = lruvec_memcg(v); + + ++*pos; + + nid = next_memory_node(nid); + if (nid == MAX_NUMNODES) { + memcg = mem_cgroup_iter(NULL, memcg, NULL); + if (!memcg) + return NULL; + + nid = first_memory_node; + } + + return get_lruvec(nid, memcg); +} + +static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec, + unsigned long max_seq, unsigned long *min_seq, + unsigned long seq) +{ + int i; + int type, tier; + int hist = lru_hist_from_seq(seq); + struct lrugen *lrugen = &lruvec->evictable; + + for (tier = 0; tier < MAX_NR_TIERS; tier++) { + seq_printf(m, " %10d", tier); + for (type = 0; type < ANON_AND_FILE; type++) { + unsigned long n[3] = {}; + + if (seq == max_seq) { + n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]); + n[1] = READ_ONCE(lrugen->avg_total[type][tier]); + + seq_printf(m, " %10luR %10luT %10lu ", n[0], n[1], n[2]); + } else if (seq == min_seq[type] || NR_HIST_GENS > 1) { + n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]); + n[1] = atomic_long_read(&lrugen->evicted[hist][type][tier]); + if (tier) + n[2] = READ_ONCE(lrugen->protected[hist][type][tier - 1]); + + seq_printf(m, " %10lur %10lue %10lup", n[0], n[1], n[2]); + } else + seq_puts(m, " 0 0 0 "); + } + seq_putc(m, '\n'); + } + + seq_puts(m, " "); + for (i = 0; i < NR_MM_STATS; i++) { + if (seq == max_seq && NR_HIST_GENS == 1) + seq_printf(m, " %10lu%c", READ_ONCE(lruvec->mm_walk.stats[hist][i]), + toupper(MM_STAT_CODES[i])); + else if (seq != max_seq && NR_HIST_GENS > 1) + seq_printf(m, " %10lu%c", READ_ONCE(lruvec->mm_walk.stats[hist][i]), + MM_STAT_CODES[i]); + else + seq_puts(m, " 0 "); + } + seq_putc(m, '\n'); +} + +static int lru_gen_seq_show(struct seq_file *m, void *v) +{ + unsigned long seq; + bool full = !debugfs_real_fops(m->file)->write; + struct lruvec *lruvec = v; + struct lrugen *lrugen = &lruvec->evictable; + int nid = lruvec_pgdat(lruvec)->node_id; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + DEFINE_MAX_SEQ(lruvec); + DEFINE_MIN_SEQ(lruvec); + + if (nid == first_memory_node) { + const char *path = memcg ? m->private : ""; + +#ifdef CONFIG_MEMCG + if (memcg) + cgroup_path(memcg->css.cgroup, m->private, PATH_MAX); +#endif + seq_printf(m, "memcg %5hu %s\n", mem_cgroup_id(memcg), path); + } + + seq_printf(m, " node %5d\n", nid); + + if (!full) + seq = min_seq[0]; + else if (max_seq >= MAX_NR_GENS) + seq = max_seq - MAX_NR_GENS + 1; + else + seq = 0; + + for (; seq <= max_seq; seq++) { + int gen, type, zone; + unsigned int msecs; + + gen = lru_gen_from_seq(seq); + msecs = jiffies_to_msecs(jiffies - READ_ONCE(lrugen->timestamps[gen])); + + seq_printf(m, " %10lu %10u", seq, msecs); + + for (type = 0; type < ANON_AND_FILE; type++) { + long size = 0; + + if (seq < min_seq[type]) { + seq_puts(m, " -0 "); + continue; + } + + for (zone = 0; zone < MAX_NR_ZONES; zone++) + size += READ_ONCE(lrugen->sizes[gen][type][zone]); + + seq_printf(m, " %10lu ", max(size, 0L)); + } + + seq_putc(m, '\n'); + + if (full) + lru_gen_seq_show_full(m, lruvec, max_seq, min_seq, seq); + } + + return 0; +} + +static const struct seq_operations lru_gen_seq_ops = { + .start = lru_gen_seq_start, + .stop = lru_gen_seq_stop, + .next = lru_gen_seq_next, + .show = lru_gen_seq_show, +}; + +static int run_aging(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + unsigned long seq, bool use_filter) +{ + DEFINE_MAX_SEQ(lruvec); + + if (seq == max_seq) + try_to_inc_max_seq(lruvec, sc, swappiness, max_seq, use_filter); + + return seq > max_seq ? -EINVAL : 0; +} + +static int run_eviction(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + unsigned long seq, unsigned long nr_to_reclaim) +{ + struct blk_plug plug; + int err = -EINTR; + DEFINE_MAX_SEQ(lruvec); + + if (seq >= max_seq - 1) + return -EINVAL; + + sc->nr_reclaimed = 0; + + blk_start_plug(&plug); + + while (!signal_pending(current)) { + DEFINE_MIN_SEQ(lruvec); + + if (seq < min_seq[!swappiness] || sc->nr_reclaimed >= nr_to_reclaim || + !evict_pages(lruvec, sc, swappiness)) { + err = 0; + break; + } + + cond_resched(); + } + + blk_finish_plug(&plug); + + return err; +} + +static int run_cmd(char cmd, int memcg_id, int nid, struct scan_control *sc, + int swappiness, unsigned long seq, unsigned long opt) +{ + struct lruvec *lruvec; + int err = -EINVAL; + struct mem_cgroup *memcg = NULL; + + if (!mem_cgroup_disabled()) { + rcu_read_lock(); + memcg = mem_cgroup_from_id(memcg_id); +#ifdef CONFIG_MEMCG + if (memcg && !css_tryget(&memcg->css)) + memcg = NULL; +#endif + rcu_read_unlock(); + + if (!memcg) + goto done; + } + if (memcg_id != mem_cgroup_id(memcg)) + goto done; + + if (nid < 0 || nid >= MAX_NUMNODES || !node_state(nid, N_MEMORY)) + goto done; + + lruvec = get_lruvec(nid, memcg); + + if (swappiness < 0) + swappiness = get_swappiness(memcg); + else if (swappiness > 200) + goto done; + + switch (cmd) { + case '+': + err = run_aging(lruvec, sc, swappiness, seq, opt); + break; + case '-': + err = run_eviction(lruvec, sc, swappiness, seq, opt); + break; + } +done: + mem_cgroup_put(memcg); + + return err; +} + +static ssize_t lru_gen_seq_write(struct file *file, const char __user *src, + size_t len, loff_t *pos) +{ + void *buf; + char *cur, *next; + unsigned int flags; + int err = 0; + struct scan_control sc = { + .may_writepage = 1, + .may_unmap = 1, + .may_swap = 1, + .reclaim_idx = MAX_NR_ZONES - 1, + .gfp_mask = GFP_KERNEL, + }; + + buf = kvmalloc(len + 1, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + if (copy_from_user(buf, src, len)) { + kvfree(buf); + return -EFAULT; + } + + next = buf; + next[len] = '\0'; + + sc.reclaim_state.mm_walk_args = alloc_mm_walk_args(); + if (!sc.reclaim_state.mm_walk_args) { + kvfree(buf); + return -ENOMEM; + } + + flags = memalloc_noreclaim_save(); + set_task_reclaim_state(current, &sc.reclaim_state); + + while ((cur = strsep(&next, ",;\n"))) { + int n; + int end; + char cmd; + unsigned int memcg_id; + unsigned int nid; + unsigned long seq; + unsigned int swappiness = -1; + unsigned long opt = -1; + + cur = skip_spaces(cur); + if (!*cur) + continue; + + n = sscanf(cur, "%c %u %u %lu %n %u %n %lu %n", &cmd, &memcg_id, &nid, + &seq, &end, &swappiness, &end, &opt, &end); + if (n < 4 || cur[end]) { + err = -EINVAL; + break; + } + + err = run_cmd(cmd, memcg_id, nid, &sc, swappiness, seq, opt); + if (err) + break; + } + + set_task_reclaim_state(current, NULL); + memalloc_noreclaim_restore(flags); + + free_mm_walk_args(sc.reclaim_state.mm_walk_args); + kvfree(buf); + + return err ? : len; +} + +static int lru_gen_seq_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &lru_gen_seq_ops); +} + +static const struct file_operations lru_gen_rw_fops = { + .open = lru_gen_seq_open, + .read = seq_read, + .write = lru_gen_seq_write, + .llseek = seq_lseek, + .release = seq_release, +}; + +static const struct file_operations lru_gen_ro_fops = { + .open = lru_gen_seq_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + +/****************************************************************************** + * initialization + ******************************************************************************/ + +void lru_gen_init_state(struct mem_cgroup *memcg, struct lruvec *lruvec) +{ + int i; + int gen, type, zone; + struct lrugen *lrugen = &lruvec->evictable; + struct lru_gen_mm_list *mm_list = get_mm_list(memcg); + + lrugen->max_seq = MIN_NR_GENS + 1; + lrugen->enabled[0] = lru_gen_enabled() && lru_gen_nr_swapfiles; + lrugen->enabled[1] = lru_gen_enabled(); + + for (i = 0; i <= MIN_NR_GENS + 1; i++) + lrugen->timestamps[i] = jiffies; + + for_each_gen_type_zone(gen, type, zone) + INIT_LIST_HEAD(&lrugen->lists[gen][type][zone]); + + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && !memcg) + spin_lock(&mm_list->lock); + + lruvec->mm_walk.seq = MIN_NR_GENS; + lruvec->mm_walk.head = &mm_list->fifo; + lruvec->mm_walk.tail = &mm_list->fifo; + init_waitqueue_head(&lruvec->mm_walk.wait); + + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && !memcg) + spin_unlock(&mm_list->lock); +} + +#ifdef CONFIG_MEMCG +void lru_gen_init_memcg(struct mem_cgroup *memcg) +{ + int nid; + + INIT_LIST_HEAD(&memcg->mm_list.fifo); + spin_lock_init(&memcg->mm_list.lock); + + for_each_node(nid) { + struct lruvec *lruvec = get_lruvec(nid, memcg); + + lru_gen_init_state(memcg, lruvec); + } +} + +void lru_gen_free_memcg(struct mem_cgroup *memcg) +{ + int nid; + + for_each_node(nid) { + int i; + struct lruvec *lruvec = get_lruvec(nid, memcg); + + for (i = 0; i < NR_BLOOM_FILTERS; i++) { + bitmap_free(lruvec->mm_walk.filters[i]); + lruvec->mm_walk.filters[i] = NULL; + } + } +} +#endif + +static int __init init_lru_gen(void) +{ + BUILD_BUG_ON(MIN_NR_GENS + 1 >= MAX_NR_GENS); + BUILD_BUG_ON(BIT(LRU_GEN_WIDTH) <= MAX_NR_GENS); + BUILD_BUG_ON(sizeof(MM_STAT_CODES) != NR_MM_STATS + 1); + + if (sysfs_create_group(mm_kobj, &lru_gen_attr_group)) + pr_err("lru_gen: failed to create sysfs group\n"); + + debugfs_create_file("lru_gen", 0644, NULL, NULL, &lru_gen_rw_fops); + debugfs_create_file("lru_gen_full", 0444, NULL, NULL, &lru_gen_ro_fops); + + return 0; +}; +late_initcall(init_lru_gen); + +#else + +static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) +{ +} + +static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +{ +} + +#endif /* CONFIG_LRU_GEN */ + static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { unsigned long nr[NR_LRU_LISTS]; @@ -2794,6 +5387,11 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) struct blk_plug plug; bool scan_adjusted; + if (lru_gen_enabled()) { + lru_gen_shrink_lruvec(lruvec, sc); + return; + } + get_scan_count(lruvec, sc, nr); /* Record the original scan target for proportional adjustments later */ @@ -3032,7 +5630,6 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) unsigned long nr_reclaimed, nr_scanned; struct lruvec *target_lruvec; bool reclaimable = false; - unsigned long file; target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat); @@ -3048,93 +5645,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) nr_reclaimed = sc->nr_reclaimed; nr_scanned = sc->nr_scanned; - /* - * Determine the scan balance between anon and file LRUs. - */ - spin_lock_irq(&target_lruvec->lru_lock); - sc->anon_cost = target_lruvec->anon_cost; - sc->file_cost = target_lruvec->file_cost; - spin_unlock_irq(&target_lruvec->lru_lock); - - /* - * Target desirable inactive:active list ratios for the anon - * and file LRU lists. - */ - if (!sc->force_deactivate) { - unsigned long refaults; - - refaults = lruvec_page_state(target_lruvec, - WORKINGSET_ACTIVATE_ANON); - if (refaults != target_lruvec->refaults[0] || - inactive_is_low(target_lruvec, LRU_INACTIVE_ANON)) - sc->may_deactivate |= DEACTIVATE_ANON; - else - sc->may_deactivate &= ~DEACTIVATE_ANON; - - /* - * When refaults are being observed, it means a new - * workingset is being established. Deactivate to get - * rid of any stale active pages quickly. - */ - refaults = lruvec_page_state(target_lruvec, - WORKINGSET_ACTIVATE_FILE); - if (refaults != target_lruvec->refaults[1] || - inactive_is_low(target_lruvec, LRU_INACTIVE_FILE)) - sc->may_deactivate |= DEACTIVATE_FILE; - else - sc->may_deactivate &= ~DEACTIVATE_FILE; - } else - sc->may_deactivate = DEACTIVATE_ANON | DEACTIVATE_FILE; - - /* - * If we have plenty of inactive file pages that aren't - * thrashing, try to reclaim those first before touching - * anonymous pages. - */ - file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE); - if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE)) - sc->cache_trim_mode = 1; - else - sc->cache_trim_mode = 0; - - /* - * Prevent the reclaimer from falling into the cache trap: as - * cache pages start out inactive, every cache fault will tip - * the scan balance towards the file LRU. And as the file LRU - * shrinks, so does the window for rotation from references. - * This means we have a runaway feedback loop where a tiny - * thrashing file LRU becomes infinitely more attractive than - * anon pages. Try to detect this based on file LRU size. - */ - if (!cgroup_reclaim(sc)) { - unsigned long total_high_wmark = 0; - unsigned long free, anon; - int z; - - free = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES); - file = node_page_state(pgdat, NR_ACTIVE_FILE) + - node_page_state(pgdat, NR_INACTIVE_FILE); - - for (z = 0; z < MAX_NR_ZONES; z++) { - struct zone *zone = &pgdat->node_zones[z]; - if (!managed_zone(zone)) - continue; - - total_high_wmark += high_wmark_pages(zone); - } - - /* - * Consider anon: if that's low too, this isn't a - * runaway file reclaim problem, but rather just - * extreme pressure. Reclaim as per usual then. - */ - anon = node_page_state(pgdat, NR_INACTIVE_ANON); - - sc->file_is_tiny = - file + free <= total_high_wmark && - !(sc->may_deactivate & DEACTIVATE_ANON) && - anon >> sc->priority; - } + prepare_scan_count(pgdat, sc); shrink_node_memcgs(pgdat, sc); @@ -3354,6 +5865,9 @@ static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat) struct lruvec *target_lruvec; unsigned long refaults; + if (lru_gen_enabled()) + return; + target_lruvec = mem_cgroup_lruvec(target_memcg, pgdat); refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_ANON); target_lruvec->refaults[0] = refaults; @@ -3724,6 +6238,11 @@ static void age_active_anon(struct pglist_data *pgdat, struct mem_cgroup *memcg; struct lruvec *lruvec; + if (lru_gen_enabled()) { + lru_gen_age_node(pgdat, sc); + return; + } + if (!can_age_anon_pages(pgdat, sc)) return; diff --git a/mm/workingset.c b/mm/workingset.c index d5b81e4f4cbe..27d504a5d998 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -187,7 +187,6 @@ static unsigned int bucket_order __read_mostly; static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction, bool workingset) { - eviction >>= bucket_order; eviction &= EVICTION_MASK; eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid; eviction = (eviction << NODES_SHIFT) | pgdat->node_id; @@ -212,10 +211,117 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat, *memcgidp = memcgid; *pgdat = NODE_DATA(nid); - *evictionp = entry << bucket_order; + *evictionp = entry; *workingsetp = workingset; } +#ifdef CONFIG_LRU_GEN + +static int page_lru_refs(struct page *page) +{ + unsigned long flags = READ_ONCE(page->flags); + + BUILD_BUG_ON(LRU_GEN_WIDTH + LRU_REFS_WIDTH > BITS_PER_LONG - EVICTION_SHIFT); + + /* see the comment on MAX_NR_TIERS */ + return flags & BIT(PG_workingset) ? (flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF : 0; +} + +/* Return a token to be stored in the shadow entry of a page being evicted. */ +static void *lru_gen_eviction(struct page *page) +{ + int hist, tier; + unsigned long token; + unsigned long min_seq; + struct lruvec *lruvec; + struct lrugen *lrugen; + int type = page_is_file_lru(page); + int refs = page_lru_refs(page); + int delta = thp_nr_pages(page); + bool workingset = PageWorkingset(page); + struct mem_cgroup *memcg = page_memcg(page); + struct pglist_data *pgdat = page_pgdat(page); + + lruvec = mem_cgroup_lruvec(memcg, pgdat); + lrugen = &lruvec->evictable; + min_seq = READ_ONCE(lrugen->min_seq[type]); + token = (min_seq << LRU_REFS_WIDTH) | refs; + + hist = lru_hist_from_seq(min_seq); + tier = lru_tier_from_refs(refs + workingset); + atomic_long_add(delta, &lrugen->evicted[hist][type][tier]); + + return pack_shadow(mem_cgroup_id(memcg), pgdat, token, workingset); +} + +/* Count a refaulted page based on the token stored in its shadow entry. */ +static void lru_gen_refault(struct page *page, void *shadow) +{ + int hist, tier, refs; + int memcg_id; + bool workingset; + unsigned long token; + unsigned long min_seq; + struct lruvec *lruvec; + struct lrugen *lrugen; + struct mem_cgroup *memcg; + struct pglist_data *pgdat; + int type = page_is_file_lru(page); + int delta = thp_nr_pages(page); + + unpack_shadow(shadow, &memcg_id, &pgdat, &token, &workingset); + if (page_pgdat(page) != pgdat) + return; + + rcu_read_lock(); + memcg = page_memcg_rcu(page); + if (mem_cgroup_id(memcg) != memcg_id) + goto unlock; + + refs = token & (BIT(LRU_REFS_WIDTH) - 1); + if (refs && !workingset) + goto unlock; + + token >>= LRU_REFS_WIDTH; + lruvec = mem_cgroup_lruvec(memcg, pgdat); + lrugen = &lruvec->evictable; + min_seq = READ_ONCE(lrugen->min_seq[type]); + if (token != (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH))) + goto unlock; + + hist = lru_hist_from_seq(min_seq); + tier = lru_tier_from_refs(refs + workingset); + atomic_long_add(delta, &lrugen->refaulted[hist][type][tier]); + mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + type, delta); + + /* + * Tiers don't offer any protection to pages accessed via page tables. + * That's what generations do. Tiers can't fully protect pages after + * their numbers of accesses has exceeded the max value. Conservatively + * count these two conditions as stalls even though they might not + * indicate any real memory pressure. + */ + if (task_in_nonseq_fault() || refs + workingset == BIT(LRU_REFS_WIDTH)) { + SetPageWorkingset(page); + mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + type, delta); + } +unlock: + rcu_read_unlock(); +} + +#else + +static void *lru_gen_eviction(struct page *page) +{ + return NULL; +} + +static void lru_gen_refault(struct page *page, void *shadow) +{ +} + +#endif /* CONFIG_LRU_GEN */ + /** * workingset_age_nonresident - age non-resident entries as LRU ages * @lruvec: the lruvec that was aged @@ -264,10 +370,14 @@ void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg) VM_BUG_ON_PAGE(page_count(page), page); VM_BUG_ON_PAGE(!PageLocked(page), page); + if (lru_gen_enabled()) + return lru_gen_eviction(page); + lruvec = mem_cgroup_lruvec(target_memcg, pgdat); /* XXX: target_memcg can be NULL, go through lruvec */ memcgid = mem_cgroup_id(lruvec_memcg(lruvec)); eviction = atomic_long_read(&lruvec->nonresident_age); + eviction >>= bucket_order; workingset_age_nonresident(lruvec, thp_nr_pages(page)); return pack_shadow(memcgid, pgdat, eviction, PageWorkingset(page)); } @@ -296,7 +406,13 @@ void workingset_refault(struct page *page, void *shadow) bool workingset; int memcgid; + if (lru_gen_enabled()) { + lru_gen_refault(page, shadow); + return; + } + unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset); + eviction <<= bucket_order; rcu_read_lock(); /* -- 2.33.1