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* [PATCH -next] fork: silence a false postive warning in __mmdrop
@ 2020-06-04 15:03 Qian Cai
  2020-07-21 17:30 ` Qian Cai
  2020-07-22 10:06 ` peterz
  0 siblings, 2 replies; 9+ messages in thread
From: Qian Cai @ 2020-06-04 15:03 UTC (permalink / raw)
  To: peterz; +Cc: mark.rutland, akpm, linux-kernel, Qian Cai

The linux-next commit bf2c59fce407 ("sched/core: Fix illegal RCU from
offline CPUs") delayed,

idle->active_mm = &init_mm;

into finish_cpu() instead of idle_task_exit() which results in a false
positive warning that was originally designed in the commit 3eda69c92d47
("kernel/fork.c: detect early free of a live mm").

 WARNING: CPU: 127 PID: 72976 at kernel/fork.c:697
 __mmdrop+0x230/0x2c0
 do_exit+0x424/0xfa0
 Call Trace:
 do_exit+0x424/0xfa0
 do_group_exit+0x64/0xd0
 sys_exit_group+0x24/0x30
 system_call_exception+0x108/0x1d0
 system_call_common+0xf0/0x278

Fixes: bf2c59fce407 ("sched/core: Fix illegal RCU from offline CPUs")
Signed-off-by: Qian Cai <cai@lca.pw>
---
 kernel/fork.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 142b23645d82..5334efd2a680 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -694,7 +694,6 @@ void __mmdrop(struct mm_struct *mm)
 {
 	BUG_ON(mm == &init_mm);
 	WARN_ON_ONCE(mm == current->mm);
-	WARN_ON_ONCE(mm == current->active_mm);
 	mm_free_pgd(mm);
 	destroy_context(mm);
 	mmu_notifier_subscriptions_destroy(mm);
-- 
2.21.0 (Apple Git-122.2)


^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2020-09-08 18:00 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-04 15:03 [PATCH -next] fork: silence a false postive warning in __mmdrop Qian Cai
2020-07-21 17:30 ` Qian Cai
2020-07-22 10:06 ` peterz
2020-07-22 13:19   ` Qian Cai
2020-07-22 13:44     ` Peter Zijlstra
2020-09-08 16:50       ` Qian Cai
2020-09-08 16:50         ` Qian Cai
2020-09-08 17:58         ` peterz
2020-09-08 17:58           ` peterz

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