Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752663AbcDZM6Y (ORCPT ); Tue, 26 Apr 2016 08:58:24 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35081 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315AbcDZM4o (ORCPT ); Tue, 26 Apr 2016 08:56:44 -0400 From: Michal Hocko To: , Andrew Morton Cc: LKML , Michal Hocko , Hugh Dickins , Davidlohr Bueso , Vlastimil Babka Subject: [PATCH 09/18] ipc, shm: make shmem attach/detach wait for mmap_sem killable Date: Tue, 26 Apr 2016 14:56:16 +0200 Message-Id: <1461675385-5934-10-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.8.0.rc3 In-Reply-To: <1461675385-5934-1-git-send-email-mhocko@kernel.org> References: <1461675385-5934-1-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1335 Lines: 45 From: Michal Hocko 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. Cc: Hugh Dickins Acked-by: Davidlohr Bueso Acked-by: Vlastimil Babka Signed-off-by: Michal Hocko --- ipc/shm.c | 9 +++++++-- 1 file 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(¤t->mm->mmap_sem); + if (down_write_killable(¤t->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 -- 2.8.0.rc3