Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751990AbbK1EjR (ORCPT ); Fri, 27 Nov 2015 23:39:17 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:33362 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751906AbbK1EjQ (ORCPT ); Fri, 27 Nov 2015 23:39:16 -0500 To: mhocko@kernel.org, linux-mm@kvack.org Cc: akpm@linux-foundation.org, torvalds@linux-foundation.org, mgorman@suse.de, rientjes@google.com, riel@redhat.com, hughd@google.com, oleg@redhat.com, andrea@kernel.org, linux-kernel@vger.kernel.org, mhocko@suse.com Subject: Re: [RFC PATCH -v2] mm, oom: introduce oom reaper From: Tetsuo Handa References: <1448467018-20603-1-git-send-email-mhocko@kernel.org> <1448640772-30147-1-git-send-email-mhocko@kernel.org> In-Reply-To: <1448640772-30147-1-git-send-email-mhocko@kernel.org> Message-Id: <201511281339.JHH78172.SLOQFOFHVFOMJt@I-love.SAKURA.ne.jp> X-Mailer: Winbiff [Version 2.51 PL2] X-Accept-Language: ja,en,zh Date: Sat, 28 Nov 2015 13:39:11 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1673 Lines: 55 Michal Hocko wrote: > for write while write but the probability is reduced considerably wrt. Is this "while write" garbage? > Users of mmap_sem which need it for write should be carefully reviewed > to use _killable waiting as much as possible and reduce allocations > requests done with the lock held to absolute minimum to reduce the risk > even further. It will be nice if we can have down_write_killable()/down_read_killable(). > The API between oom killer and oom reaper is quite trivial. wake_oom_reaper > updates mm_to_reap with cmpxchg to guarantee only NUll->mm transition NULL->mm > and oom_reaper clear this atomically once it is done with the work. Can't oom_reaper() become as compact as below? diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 3f22efc..c2ab7f9 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -472,21 +472,10 @@ static void oom_reap_vmas(struct mm_struct *mm) static int oom_reaper(void *unused) { - DEFINE_WAIT(wait); - while (true) { - struct mm_struct *mm; - - prepare_to_wait(&oom_reaper_wait, &wait, TASK_UNINTERRUPTIBLE); - mm = READ_ONCE(mm_to_reap); - if (!mm) { - freezable_schedule(); - finish_wait(&oom_reaper_wait, &wait); - } else { - finish_wait(&oom_reaper_wait, &wait); - oom_reap_vmas(mm); - WRITE_ONCE(mm_to_reap, NULL); - } + wait_event_freezable(oom_reaper_wait, mm_to_reap); + oom_reap_vmas(mm_to_reap); + mm_to_reap = NULL; } return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/