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Groups > linux.kernel > #1543347
| From | "Kirill A. Shutemov" <kirill@shutemov.name> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: crash during oom reaper (was: Re: [PATCH 4/4] [RFC!] mm: 'struct mm_struct' reference counting debugging) |
| Date | 2016-12-16 11:50 +0100 |
| Message-ID | <sOYfn-2oy-3@gated-at.bofh.it> (permalink) |
| References | <sOWwW-19z-41@gated-at.bofh.it> <sOWGD-1t7-59@gated-at.bofh.it> <sOWGD-1t7-57@gated-at.bofh.it> <sOXjk-1Nk-25@gated-at.bofh.it> <sOXMm-2df-27@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Dec 16, 2016 at 11:11:13AM +0100, Michal Hocko wrote:
> On Fri 16-12-16 10:43:52, Vegard Nossum wrote:
> [...]
> > I don't think it's a bug in the OOM reaper itself, but either of the
> > following two patches will fix the problem (without my understand how or
> > why):
> >
> > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> > index ec9f11d4f094..37b14b2e2af4 100644
> > --- a/mm/oom_kill.c
> > +++ b/mm/oom_kill.c
> > @@ -485,7 +485,7 @@ static bool __oom_reap_task_mm(struct task_struct *tsk,
> > struct mm_struct *mm)
> > */
> > mutex_lock(&oom_lock);
> >
> > - if (!down_read_trylock(&mm->mmap_sem)) {
> > + if (!down_write_trylock(&mm->mmap_sem)) {
>
> __oom_reap_task_mm is basically the same thing as MADV_DONTNEED and that
> doesn't require the exlusive mmap_sem. So this looks correct to me.
BTW, shouldn't we filter out all VM_SPECIAL VMAs there? Or VM_PFNMAP at
least.
MADV_DONTNEED doesn't touch VM_PFNMAP, but I don't see anything matching
on __oom_reap_task_mm() side.
Other difference is that you use unmap_page_range() witch doesn't touch
mmu_notifiers. MADV_DONTNEED goes via zap_page_range(), which invalidates
the range. Not sure if it can make any difference here.
--
Kirill A. Shutemov
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[PATCH 1/4] mm: add new mmgrab() helper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 10:00 +0100
Re: [PATCH 4/4] [RFC!] mm: 'struct mm_struct' reference counting debugging Michal Hocko <mhocko@kernel.org> - 2016-12-16 10:10 +0100
Re: [PATCH 4/4] [RFC!] mm: 'struct mm_struct' reference counting debugging Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 10:50 +0100
crash during oom reaper (was: Re: [PATCH 4/4] [RFC!] mm: 'struct mm_struct' reference counting debugging) Michal Hocko <mhocko@kernel.org> - 2016-12-16 11:20 +0100
Re: crash during oom reaper (was: Re: [PATCH 4/4] [RFC!] mm: 'struct mm_struct' reference counting debugging) "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-16 11:50 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-16 13:00 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-16 13:20 +0100
Re: crash during oom reaper "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-16 13:50 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-16 14:00 +0100
Re: crash during oom reaper "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-16 14:10 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-16 14:20 +0100
Re: crash during oom reaper Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-12-18 14:50 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-18 17:10 +0100
Re: crash during oom reaper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 14:20 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-16 15:10 +0100
Re: crash during oom reaper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 15:30 +0100
Re: crash during oom reaper Michal Hocko <mhocko@kernel.org> - 2016-12-16 15:50 +0100
Re: crash during oom reaper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 16:00 +0100
Re: crash during oom reaper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 15:10 +0100
Re: [PATCH 3/4] mm: use mmget_not_zero() helper Michal Hocko <mhocko@kernel.org> - 2016-12-16 10:30 +0100
Re: [PATCH 2/4] mm: add new mmget() helper Michal Hocko <mhocko@kernel.org> - 2016-12-16 10:30 +0100
[PATCH 3/4] mm: use mmget_not_zero() helper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 10:40 +0100
[PATCH 2/4] mm: add new mmget() helper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 10:50 +0100
Re: [PATCH 1/4] mm: add new mmgrab() helper Michal Hocko <mhocko@kernel.org> - 2016-12-16 10:50 +0100
Re: [PATCH 1/4] mm: add new mmgrab() helper Peter Zijlstra <peterz@infradead.org> - 2016-12-16 11:00 +0100
Re: [PATCH 1/4] mm: add new mmgrab() helper "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-16 11:20 +0100
Re: [PATCH 1/4] mm: add new mmgrab() helper Michal Hocko <mhocko@kernel.org> - 2016-12-16 11:50 +0100
Re: [PATCH 1/4] mm: add new mmgrab() helper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 12:00 +0100
Re: [PATCH 1/4] mm: add new mmgrab() helper Vegard Nossum <vegard.nossum@oracle.com> - 2016-12-16 12:20 +0100
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