diff options
Diffstat (limited to 'broken-sleep-5.4.48+.patch')
-rw-r--r-- | broken-sleep-5.4.48+.patch | 152 |
1 files changed, 0 insertions, 152 deletions
diff --git a/broken-sleep-5.4.48+.patch b/broken-sleep-5.4.48+.patch deleted file mode 100644 index e922de302b1f..000000000000 --- a/broken-sleep-5.4.48+.patch +++ /dev/null @@ -1,152 +0,0 @@ -From f7757368e0f0b3e108088ca7b5b8abda6faa7ebc Mon Sep 17 00:00:00 2001 -From: Peter Zijlstra <peterz@infradead.org> -Date: Wed, 1 Apr 2020 17:40:33 -0400 -Subject: sched/core: Fix illegal RCU from offline CPUs - -[ Upstream commit bf2c59fce4074e55d622089b34be3a6bc95484fb ] - -In the CPU-offline process, it calls mmdrop() after idle entry and the -subsequent call to cpuhp_report_idle_dead(). Once execution passes the -call to rcu_report_dead(), RCU is ignoring the CPU, which results in -lockdep complaining when mmdrop() uses RCU from either memcg or -debugobjects below. - -Fix it by cleaning up the active_mm state from BP instead. Every arch -which has CONFIG_HOTPLUG_CPU should have already called idle_task_exit() -from AP. The only exception is parisc because it switches them to -&init_mm unconditionally (see smp_boot_one_cpu() and smp_cpu_init()), -but the patch will still work there because it calls mmgrab(&init_mm) in -smp_cpu_init() and then should call mmdrop(&init_mm) in finish_cpu(). - - WARNING: suspicious RCU usage - ----------------------------- - kernel/workqueue.c:710 RCU or wq_pool_mutex should be held! - - other info that might help us debug this: - - RCU used illegally from offline CPU! - Call Trace: - dump_stack+0xf4/0x164 (unreliable) - lockdep_rcu_suspicious+0x140/0x164 - get_work_pool+0x110/0x150 - __queue_work+0x1bc/0xca0 - queue_work_on+0x114/0x120 - css_release+0x9c/0xc0 - percpu_ref_put_many+0x204/0x230 - free_pcp_prepare+0x264/0x570 - free_unref_page+0x38/0xf0 - __mmdrop+0x21c/0x2c0 - idle_task_exit+0x170/0x1b0 - pnv_smp_cpu_kill_self+0x38/0x2e0 - cpu_die+0x48/0x64 - arch_cpu_idle_dead+0x30/0x50 - do_idle+0x2f4/0x470 - cpu_startup_entry+0x38/0x40 - start_secondary+0x7a8/0xa80 - start_secondary_resume+0x10/0x14 - -Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> -Signed-off-by: Qian Cai <cai@lca.pw> -Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> -Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) -Link: https://lkml.kernel.org/r/20200401214033.8448-1-cai@lca.pw -Signed-off-by: Sasha Levin <sashal@kernel.org> ---- - arch/powerpc/platforms/powernv/smp.c | 1 - - include/linux/sched/mm.h | 2 ++ - kernel/cpu.c | 18 +++++++++++++++++- - kernel/sched/core.c | 5 +++-- - 4 files changed, 22 insertions(+), 4 deletions(-) - -diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c -index 13e251699346..b2ba3e95bda7 100644 ---- a/arch/powerpc/platforms/powernv/smp.c -+++ b/arch/powerpc/platforms/powernv/smp.c -@@ -167,7 +167,6 @@ static void pnv_smp_cpu_kill_self(void) - /* Standard hot unplug procedure */ - - idle_task_exit(); -- current->active_mm = NULL; /* for sanity */ - cpu = smp_processor_id(); - DBG("CPU%d offline\n", cpu); - generic_set_cpu_dead(cpu); -diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h -index c49257a3b510..a132d875d351 100644 ---- a/include/linux/sched/mm.h -+++ b/include/linux/sched/mm.h -@@ -49,6 +49,8 @@ static inline void mmdrop(struct mm_struct *mm) - __mmdrop(mm); - } - -+void mmdrop(struct mm_struct *mm); -+ - /* - * This has to be called after a get_task_mm()/mmget_not_zero() - * followed by taking the mmap_sem for writing before modifying the -diff --git a/kernel/cpu.c b/kernel/cpu.c -index d7890c1285bf..7527825ac7da 100644 ---- a/kernel/cpu.c -+++ b/kernel/cpu.c -@@ -3,6 +3,7 @@ - * - * This code is licenced under the GPL. - */ -+#include <linux/sched/mm.h> - #include <linux/proc_fs.h> - #include <linux/smp.h> - #include <linux/init.h> -@@ -564,6 +565,21 @@ static int bringup_cpu(unsigned int cpu) - return bringup_wait_for_ap(cpu); - } - -+static int finish_cpu(unsigned int cpu) -+{ -+ struct task_struct *idle = idle_thread_get(cpu); -+ struct mm_struct *mm = idle->active_mm; -+ -+ /* -+ * idle_task_exit() will have switched to &init_mm, now -+ * clean up any remaining active_mm state. -+ */ -+ if (mm != &init_mm) -+ idle->active_mm = &init_mm; -+ mmdrop(mm); -+ return 0; -+} -+ - /* - * Hotplug state machine related functions - */ -@@ -1434,7 +1450,7 @@ static struct cpuhp_step cpuhp_hp_states[] = { - [CPUHP_BRINGUP_CPU] = { - .name = "cpu:bringup", - .startup.single = bringup_cpu, -- .teardown.single = NULL, -+ .teardown.single = finish_cpu, - .cant_stop = true, - }, - /* Final state before CPU kills itself */ -diff --git a/kernel/sched/core.c b/kernel/sched/core.c -index e99d326fa569..4874e1468279 100644 ---- a/kernel/sched/core.c -+++ b/kernel/sched/core.c -@@ -6177,13 +6177,14 @@ void idle_task_exit(void) - struct mm_struct *mm = current->active_mm; - - BUG_ON(cpu_online(smp_processor_id())); -+ BUG_ON(current != this_rq()->idle); - - if (mm != &init_mm) { - switch_mm(mm, &init_mm, current); -- current->active_mm = &init_mm; - finish_arch_post_lock_switch(); - } -- mmdrop(mm); -+ -+ /* finish_cpu(), as ran on the BP, will clean up the active_mm state */ - } - - /* --- -cgit 1.2.3-1.el7 - |