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authorMichal Hocko <mhocko@suse.com>2016-05-23 16:25:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-23 17:04:14 -0700
commit91f4f94ea3f2eabb4cee68149a31e30f84a993dd (patch)
tree1f137113b14e0a66cf24a8c8a32650095f7234d9
parent7c051267931a9be9c6620cc17b362bc6ee6dedc8 (diff)
downloadlinux-91f4f94ea3f2eabb4cee68149a31e30f84a993dd.tar.gz
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>
-rw-r--r--ipc/shm.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 331fc1b0b3c7..13282510bc0d 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -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