Messages in this thread | | | Subject | Re: [PATCH] mm, fork: make dup_mmap wait for mmap_sem for write killable | From | Vlastimil Babka <> | Date | Fri, 11 Mar 2016 12:12:12 +0100 |
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On 02/29/2016 07:07 PM, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > dup_mmap needs to lock current's mm mmap_sem for write. If the waiting > task gets killed by the oom killer it would block oom_reaper from > asynchronous address space reclaim and reduce the chances of timely OOM > resolving. Wait for the lock in the killable mode and return with EINTR > if the task got killed while waiting. > > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Oleg Nesterov <oleg@redhat.com> > Cc: Konstantin Khlebnikov <koct9i@gmail.com> > Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> --- > kernel/fork.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index d277e83ed3e0..139968026b76 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -413,7 +413,10 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) > unsigned long charge; > > uprobe_start_dup_mmap(); > - down_write(&oldmm->mmap_sem); > + if (down_write_killable(&oldmm->mmap_sem)) { > + retval = -EINTR; > + goto fail_uprobe_end; > + } > flush_cache_dup_mm(oldmm); > uprobe_dup_mmap(oldmm, mm); > /* > @@ -525,6 +528,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) > up_write(&mm->mmap_sem); > flush_tlb_mm(oldmm); > up_write(&oldmm->mmap_sem); > +fail_uprobe_end: > uprobe_end_dup_mmap(); > return retval; > fail_nomem_anon_vma_fork: >
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