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ipc, shm: make shmem attach/detach wait for mmap_sem killable 

shmat and shmdt rely on mmap_sem for write.  If the waiting task gets
killed by the oom killer it would block oom_reaper from asynchronous
address space reclaim and reduce the chances of timely OOM resolving.
Wait for the lock in the killable mode and return with EINTR if the task
got killed while waiting.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2016-05-23 16:25:51 -07:00 committed by Linus Torvalds
parent 7c05126793
commit 91f4f94ea3
1 changed files with 7 additions and 2 deletions
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9
ipc/shm.c
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@ -1200,7 +1200,11 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
if (err)
goto out_fput;
down_write(&current->mm->mmap_sem);
if (down_write_killable(&current->mm->mmap_sem)) {
err = -EINTR;
goto out_fput;
}
if (addr && !(shmflg & SHM_REMAP)) {
err = -EINVAL;
if (addr + size < addr)
@ -1271,7 +1275,8 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
if (addr & ~PAGE_MASK)
return retval;
down_write(&mm->mmap_sem);
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
/*
* This function tries to be smart and unmap shm segments that