The patch titled
Subject: mm, oom: remove oom_lock from exit_mmap()
has been added to the -mm tree. Its filename is
mm-oom-remove-oom_lock-from-exit_mmap.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-oom-remove-oom_lock-from-exit_mmap.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-oom-remove-oom_lock-from-exit_mmap.patch
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------------------------------------------------------
From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: mm, oom: remove oom_lock from exit_mmap()
oom_lock isn't needed for __oom_reap_task_mm(). If MMF_UNSTABLE is
already set for the mm, we can simply back out immediately since oom
reaping is already in progress (or done).
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1807121432370.170100@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN mm/mmap.c~mm-oom-remove-oom_lock-from-exit_mmap mm/mmap.c
--- a/mm/mmap.c~mm-oom-remove-oom_lock-from-exit_mmap
+++ a/mm/mmap.c
@@ -3081,9 +3081,7 @@ void exit_mmap(struct mm_struct *mm)
* to mmu_notifier_release(mm) ensures mmu notifier callbacks in
* __oom_reap_task_mm() will not block.
*/
- mutex_lock(&oom_lock);
__oom_reap_task_mm(mm);
- mutex_unlock(&oom_lock);
/*
* Now, set MMF_UNSTABLE to avoid racing with the oom reaper.
diff -puN mm/oom_kill.c~mm-oom-remove-oom_lock-from-exit_mmap mm/oom_kill.c
--- a/mm/oom_kill.c~mm-oom-remove-oom_lock-from-exit_mmap
+++ a/mm/oom_kill.c
@@ -496,9 +496,11 @@ void __oom_reap_task_mm(struct mm_struct
* Tell all users of get_user/copy_from_user etc... that the content
* is no longer stable. No barriers really needed because unmapping
* should imply barriers already and the reader would hit a page fault
- * if it stumbled over a reaped memory.
+ * if it stumbled over a reaped memory. If MMF_UNSTABLE is already set,
+ * reaping as already occurred so nothing left to do.
*/
- set_bit(MMF_UNSTABLE, &mm->flags);
+ if (test_and_set_bit(MMF_UNSTABLE, &mm->flags))
+ return;
for (vma = mm->mmap ; vma; vma = vma->vm_next) {
if (!can_madv_dontneed_vma(vma))
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
mm-oom-fix-unnecessary-killing-of-additional-processes.patch
mm-oom-remove-oom_lock-from-exit_mmap.patch
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