From: Michal Hocko <mhocko@xxxxxxxx> Subject: 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@xxxxxxxx> Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/coredump.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN fs/coredump.c~coredump-make-coredump_wait-wait-for-mmap_sem-for-write-killable fs/coredump.c --- a/fs/coredump.c~coredump-make-coredump_wait-wait-for-mmap_sem-for-write-killable +++ a/fs/coredump.c @@ -413,7 +413,9 @@ static int coredump_wait(int exit_code, 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
