From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13A31C6778A for ; Tue, 24 Jul 2018 14:18:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C955B20856 for ; Tue, 24 Jul 2018 14:18:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C955B20856 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388510AbeGXPYd (ORCPT ); Tue, 24 Jul 2018 11:24:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:52332 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388445AbeGXPYd (ORCPT ); Tue, 24 Jul 2018 11:24:33 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 55FE1AD71; Tue, 24 Jul 2018 14:17:49 +0000 (UTC) Date: Tue, 24 Jul 2018 16:17:47 +0200 From: Michal Hocko To: Andrew Morton Cc: LKML , linux-mm@kvack.org, "David (ChunMing) Zhou" , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Alex Deucher , David Airlie , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Doug Ledford , Jason Gunthorpe , Mike Marciniszyn , Dennis Dalessandro , Sudeep Dutt , Ashutosh Dixit , Dimitri Sivanich , Boris Ostrovsky , Juergen Gross , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrea Arcangeli , Felix Kuehling , kvm@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-rdma@vger.kernel.org, xen-devel@lists.xenproject.org, Christian =?iso-8859-1?Q?K=F6nig?= , David Rientjes , Leon Romanovsky Subject: Re: [PATCH] mm, oom: distinguish blockable mode for mmu notifiers Message-ID: <20180724141747.GP28386@dhcp22.suse.cz> References: <20180716115058.5559-1-mhocko@kernel.org> <20180720170902.d1137060c23802d55426aa03@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180720170902.d1137060c23802d55426aa03@linux-foundation.org> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 20-07-18 17:09:02, Andrew Morton wrote: [...] > - Undocumented return value. > > - comment "failed to reap part..." is misleading - sounds like it's > referring to something which happened in the past, is in fact > referring to something which might happen in the future. > > - fails to call trace_finish_task_reaping() in one case > > - code duplication. > > - Increases mmap_sem hold time a little by moving > trace_finish_task_reaping() inside the locked region. So sue me ;) > > - Sharing the finish: path means that the trace event won't > distinguish between the two sources of finishing. > > Please take a look? oom_reap_task_mm should return false when __oom_reap_task_mm return false. This is what my patch did but it seems this changed by http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-oom-remove-oom_lock-from-oom_reaper.patch so that one should be fixed. diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 104ef4a01a55..88657e018714 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -565,7 +565,7 @@ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) /* failed to reap part of the address space. Try again later */ if (!__oom_reap_task_mm(mm)) { up_read(&mm->mmap_sem); - return true; + return false; } pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", On top of that the proposed cleanup looks as follows: diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 88657e018714..4e185a282b3d 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -541,8 +541,16 @@ bool __oom_reap_task_mm(struct mm_struct *mm) return ret; } +/* + * Reaps the address space of the give task. + * + * Returns true on success and false if none or part of the address space + * has been reclaimed and the caller should retry later. + */ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) { + bool ret = true; + if (!down_read_trylock(&mm->mmap_sem)) { trace_skip_task_reaping(tsk->pid); return false; @@ -555,28 +563,28 @@ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) * down_write();up_write() cycle in exit_mmap(). */ if (test_bit(MMF_OOM_SKIP, &mm->flags)) { - up_read(&mm->mmap_sem); trace_skip_task_reaping(tsk->pid); - return true; + goto out_unlock; } trace_start_task_reaping(tsk->pid); /* failed to reap part of the address space. Try again later */ - if (!__oom_reap_task_mm(mm)) { - up_read(&mm->mmap_sem); - return false; - } + ret = __oom_reap_task_mm(mm); + if (!ret) + goto out_finish; pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", task_pid_nr(tsk), tsk->comm, K(get_mm_counter(mm, MM_ANONPAGES)), K(get_mm_counter(mm, MM_FILEPAGES)), K(get_mm_counter(mm, MM_SHMEMPAGES))); +out_finish: + trace_finish_task_reaping(tsk->pid); +out_unlock: up_read(&mm->mmap_sem); - trace_finish_task_reaping(tsk->pid); - return true; + return ret; } #define MAX_OOM_REAP_RETRIES 10 -- Michal Hocko SUSE Labs