Re: [PATCH 11/18] coredump: make coredump_wait wait for mma_sem for write killable

From	Vlastimil Babka <vbabka@suse.cz>
Newsgroups	linux.kernel
Subject	Re: [PATCH 11/18] coredump: make coredump_wait wait for mma_sem for write killable
Date	2016-03-11 13:00 +0100
Message-ID	<rbtTB-5I7-27@gated-at.bofh.it> (permalink)
References	<r7w3D-3yu-3@gated-at.bofh.it> <r7w3D-3yu-5@gated-at.bofh.it> <rbtAe-5vz-23@gated-at.bofh.it>
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On 03/11/2016 12:32 PM, Vlastimil Babka wrote:
> 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>

Forgot to point out typo in Subject which makes it hard to grep for mmap_sem

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Re: [PATCH 11/18] coredump: make coredump_wait wait for mma_sem for  write killable Vlastimil Babka <vbabka@suse.cz> - 2016-03-11 13:00 +0100
  Re: [PATCH 11/18] coredump: make coredump_wait wait for mma_sem for  write killable Michal Hocko <mhocko@kernel.org> - 2016-03-11 13:50 +0100

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