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authorMichal Hocko <mhocko@suse.com>2016-05-23 16:25:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-23 17:04:14 -0700
commit4136c26b65d12d0c5ef58b7d30dc0aa2a11ed491 (patch)
treeacd092b56a44a3f87027e27ac93900ce4fa560b1
parent69048176078adda4087a648c9b1812ddd800fad1 (diff)
coredump: make coredump_wait wait for mmap_sem for write killable
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. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/coredump.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
index 492c2db25dc9..38a7ab87e10a 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -413,7 +413,9 @@ 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);