| From | Michal Hocko <> | Subject | [PATCH 11/18] coredump: make coredump_wait wait for mma_sem for write killable | Date | Mon, 29 Feb 2016 14:26:50 +0100 |
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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> --- 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); -- 2.7.0
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