| Subject | Re: [PATCH 11/18] coredump: make coredump_wait wait for mma_sem for write killable | From | Vlastimil Babka <> | Date | Fri, 11 Mar 2016 12:32:55 +0100 |
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On 02/29/2016 02:26 PM, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > coredump_wait waits for mmap_sem for write currently which can > prevent oom_reaper to reclaim the oom victims address space > asynchronously because that requires mmap_sem for read. This might > happen if the oom victim is multi threaded and some thread(s) is > holding mmap_sem for read (e.g. page fault) and it is stuck in > the page allocator while other thread(s) reached coredump_wait > already. > > This patch simply uses down_write_killable and bails out with EINTR > if the lock got interrupted by the fatal signal. do_coredump will > return right away and do_group_exit will take care to zap the whole > thread group. > > Cc: Oleg Nesterov <oleg@redhat.com> > Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> --- > fs/coredump.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/coredump.c b/fs/coredump.c > index 9ea87e9fdccf..6b8aa1629891 100644 > --- a/fs/coredump.c > +++ b/fs/coredump.c > @@ -410,7 +410,9 @@ static int coredump_wait(int exit_code, struct core_state *core_state) > core_state->dumper.task = tsk; > core_state->dumper.next = NULL; > > - down_write(&mm->mmap_sem); > + if (down_write_killable(&mm->mmap_sem)) > + return -EINTR; > + > if (!mm->core_state) > core_waiters = zap_threads(tsk, mm, core_state, exit_code); > up_write(&mm->mmap_sem); >
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