From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f42.google.com (mail-wm0-f42.google.com [74.125.82.42]) by kanga.kvack.org (Postfix) with ESMTP id F37156B025E for ; Tue, 12 Apr 2016 05:19:22 -0400 (EDT) Received: by mail-wm0-f42.google.com with SMTP id a140so45293559wma.0 for ; Tue, 12 Apr 2016 02:19:22 -0700 (PDT) Received: from mail-wm0-f66.google.com (mail-wm0-f66.google.com. [74.125.82.66]) by mx.google.com with ESMTPS id k10si33333398wjn.38.2016.04.12.02.19.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Apr 2016 02:19:21 -0700 (PDT) Received: by mail-wm0-f66.google.com with SMTP id a140so3664988wma.2 for ; Tue, 12 Apr 2016 02:19:21 -0700 (PDT) From: Michal Hocko Subject: [PATCH] oom: consider multi-threaded tasks in task_will_free_mem Date: Tue, 12 Apr 2016 11:19:16 +0200 Message-Id: <1460452756-15491-1-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Oleg Nesterov , David Rientjes , linux-mm@kvack.org, LKML , Michal Hocko From: Michal Hocko task_will_free_mem is a misnomer for a more complex PF_EXITING test for early break out from the oom killer because it is believed that such a task would release its memory shortly and so we do not have to select an oom victim and perform a disruptive action. Currently we make sure that the given task is not participating in the core dumping because it might get blocked for a long time - see d003f371b270 ("oom: don't assume that a coredumping thread will exit soon"). The check can still do better though. We shouldn't consider the task unless the whole thread group is going down. This is rather unlikely but not impossible. A single exiting thread would surely leave all the address space behind. If we are really unlucky it might get stuck on the exit path and keep its TIF_MEMDIE and so block the oom killer. Signed-off-by: Michal Hocko --- Hi, I hope I got it right but I would really appreciate if Oleg found some time and double checked after me. The fix is more cosmetic than anything else but I guess it is worth it. Thanks! include/linux/oom.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/include/linux/oom.h b/include/linux/oom.h index 628a43242a34..b09c7dc523ff 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -102,13 +102,24 @@ extern struct task_struct *find_lock_task_mm(struct task_struct *p); static inline bool task_will_free_mem(struct task_struct *task) { + struct signal_struct *sig = task->signal; + /* * A coredumping process may sleep for an extended period in exit_mm(), * so the oom killer cannot assume that the process will promptly exit * and release memory. */ - return (task->flags & PF_EXITING) && - !(task->signal->flags & SIGNAL_GROUP_COREDUMP); + if (sig->flags & SIGNAL_GROUP_COREDUMP) + return false; + + if (!(task->flags & PF_EXITING)) + return false; + + /* Make sure that the whole thread group is going down */ + if (!thread_group_empty(task) && !(sig->flags & SIGNAL_GROUP_EXIT)) + return false; + + return true; } /* sysctls */ -- 2.8.0.rc3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org