From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031239AbbD1Wuw (ORCPT ); Tue, 28 Apr 2015 18:50:52 -0400 Received: from mail-ie0-f176.google.com ([209.85.223.176]:35927 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030966AbbD1Wut (ORCPT ); Tue, 28 Apr 2015 18:50:49 -0400 Date: Tue, 28 Apr 2015 15:50:46 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Greg Kroah-Hartman cc: =?UTF-8?Q?Arve_Hj=C3=B8nnev=C3=A5g?= , Riley Andrews , Andrew Morton , Johannes Weiner , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, devel@driverdev.osuosl.org Subject: [patch resend] android, lmk: avoid setting TIF_MEMDIE if process has already exited In-Reply-To: Message-ID: References: <1427264236-17249-1-git-send-email-hannes@cmpxchg.org> <1427264236-17249-4-git-send-email-hannes@cmpxchg.org> <20150326110532.GB18560@cmpxchg.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="531381512-275516743-1430261448=:24802" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --531381512-275516743-1430261448=:24802 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT TIF_MEMDIE should not be set on a process if it does not have a valid ->mm, and this is protected by task_lock(). If TIF_MEMDIE gets set after the mm has detached, and the process fails to exit, then the oom killer will defer forever waiting for it to exit. Make sure that the mm is still valid before setting TIF_MEMDIE by way of mark_tsk_oom_victim(). Cc: "Arve Hjønnevåg" Cc: Riley Andrews Acked-by: Michal Hocko Signed-off-by: David Rientjes --- drivers/staging/android/lowmemorykiller.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -156,20 +156,27 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) p->pid, p->comm, oom_score_adj, tasksize); } if (selected) { - lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", - selected->pid, selected->comm, - selected_oom_score_adj, selected_tasksize); - lowmem_deathpending_timeout = jiffies + HZ; + task_lock(selected); + if (!selected->mm) { + /* Already exited, cannot do mark_tsk_oom_victim() */ + task_unlock(selected); + goto out; + } /* * FIXME: lowmemorykiller shouldn't abuse global OOM killer * infrastructure. There is no real reason why the selected * task should have access to the memory reserves. */ mark_tsk_oom_victim(selected); + task_unlock(selected); + lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", + selected->pid, selected->comm, + selected_oom_score_adj, selected_tasksize); + lowmem_deathpending_timeout = jiffies + HZ; send_sig(SIGKILL, selected, 0); rem += selected_tasksize; } - +out: lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n", sc->nr_to_scan, sc->gfp_mask, rem); rcu_read_unlock(); --531381512-275516743-1430261448=:24802--