From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) by kanga.kvack.org (Postfix) with ESMTP id B643D8E00F9 for ; Sat, 26 Jan 2019 08:11:11 -0500 (EST) Received: by mail-oi1-f200.google.com with SMTP id t83so6104403oie.16 for ; Sat, 26 Jan 2019 05:11:11 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id q205si2625807oib.203.2019.01.26.05.11.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 26 Jan 2019 05:11:10 -0800 (PST) Subject: [PATCH v2] oom, oom_reaper: do not enqueue same task twice References: <20190117122535.njcbqhlmzozdkncw@mikami> <1d36b181-cbaf-6694-1a31-2f7f55d15675@gmail.com> <96ef6615-a5df-30af-b4dc-417a18ca63f1@gmail.com> <1cdbef13-564d-61a6-95f4-579d2cad243d@gmail.com> <20190125163731.GJ50184@devbig004.ftw2.facebook.com> <480296c4-ed7a-3265-e84a-298e42a0f1d5@I-love.SAKURA.ne.jp> <6da6ca69-5a6e-a9f6-d091-f89a8488982a@gmail.com> <72aa8863-a534-b8df-6b9e-f69cf4dd5c4d@i-love.sakura.ne.jp> <33a07810-6dbc-36be-5bb6-a279773ccf69@i-love.sakura.ne.jp> <34e97b46-0792-cc66-e0f2-d72576cdec59@i-love.sakura.ne.jp> <2b0c7d6c-c58a-da7d-6f0a-4900694ec2d3@gmail.com> From: Tetsuo Handa Message-ID: <1d161137-55a5-126f-b47e-b2625bd798ca@i-love.sakura.ne.jp> Date: Sat, 26 Jan 2019 22:10:52 +0900 MIME-Version: 1.0 In-Reply-To: <2b0c7d6c-c58a-da7d-6f0a-4900694ec2d3@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: =?UTF-8?Q?Arkadiusz_Mi=c5=9bkiewicz?= , Andrew Morton Cc: Tejun Heo , cgroups@vger.kernel.org, Aleksa Sarai , Jay Kamat , Roman Gushchin , Michal Hocko , Johannes Weiner , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm On 2019/01/26 20:29, Arkadiusz Miśkiewicz wrote: > On 26/01/2019 12:09, Tetsuo Handa wrote: >> Arkadiusz, will you try this patch? > > > Works. Several tries and always getting 0 pids.current after ~1s. > Thank you for testing. I updated this patch to use tsk->signal->oom_mm (a snapshot of tsk->mm saved by mark_oom_victim(tsk)) rather than raw tsk->mm so that we don't need to worry about possibility of changing tsk->mm across multiple wake_oom_reaper(tsk) calls. >>From 9c9e935fc038342c48461aabca666f1b544e32b1 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Sat, 26 Jan 2019 21:57:25 +0900 Subject: [PATCH v2] oom, oom_reaper: do not enqueue same task twice Arkadiusz reported that enabling memcg's group oom killing causes strange memcg statistics where there is no task in a memcg despite the number of tasks in that memcg is not 0. It turned out that there is a bug in wake_oom_reaper() which allows enqueuing same task twice which makes impossible to decrease the number of tasks in that memcg due to a refcount leak. This bug existed since the OOM reaper became invokable from task_will_free_mem(current) path in out_of_memory() in Linux 4.7, but memcg's group oom killing made it easier to trigger this bug by calling wake_oom_reaper() on the same task from one out_of_memory() request. Fix this bug using an approach used by commit 855b018325737f76 ("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task"). As a side effect of this patch, this patch also avoids enqueuing multiple threads sharing memory via task_will_free_mem(current) path. Signed-off-by: Tetsuo Handa Reported-by: Arkadiusz Miśkiewicz Tested-by: Arkadiusz Miśkiewicz Fixes: af8e15cc85a25315 ("oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head") --- mm/oom_kill.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index f0e8cd9..057bfee 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -505,14 +505,6 @@ bool __oom_reap_task_mm(struct mm_struct *mm) struct vm_area_struct *vma; bool ret = true; - /* - * Tell all users of get_user/copy_from_user etc... that the content - * is no longer stable. No barriers really needed because unmapping - * should imply barriers already and the reader would hit a page fault - * if it stumbled over a reaped memory. - */ - set_bit(MMF_UNSTABLE, &mm->flags); - for (vma = mm->mmap ; vma; vma = vma->vm_next) { if (!can_madv_dontneed_vma(vma)) continue; @@ -647,8 +639,13 @@ static int oom_reaper(void *unused) static void wake_oom_reaper(struct task_struct *tsk) { - /* tsk is already queued? */ - if (tsk == oom_reaper_list || tsk->oom_reaper_list) + /* + * Tell all users of get_user/copy_from_user etc... that the content + * is no longer stable. No barriers really needed because unmapping + * should imply barriers already and the reader would hit a page fault + * if it stumbled over a reaped memory. + */ + if (test_and_set_bit(MMF_UNSTABLE, &tsk->signal->oom_mm->flags)) return; get_task_struct(tsk); -- 1.8.3.1 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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=unavailable 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 EC419C282C7 for ; Sat, 26 Jan 2019 13:11:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8F7AC21872 for ; Sat, 26 Jan 2019 13:11:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F7AC21872 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F058A8E00FA; Sat, 26 Jan 2019 08:11:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EDCC68E00F9; Sat, 26 Jan 2019 08:11:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DF2878E00FA; Sat, 26 Jan 2019 08:11:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) by kanga.kvack.org (Postfix) with ESMTP id B643D8E00F9 for ; Sat, 26 Jan 2019 08:11:11 -0500 (EST) Received: by mail-oi1-f200.google.com with SMTP id t83so6104403oie.16 for ; Sat, 26 Jan 2019 05:11:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:subject:to:cc :references:from:message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=Hsx9krwA9P8nQNKjs4bhZ+Iq/VrFfAd1tSDsq96+7Po=; b=GB3xx5kIEhGUOGsSZGyt24/iRWT55237CqbQUv7k/oSaY+f03AG4v/+gjhr5s7t6R3 NyTsyEtYejMEwQLFc/bNZQRsVjYneWEwwwMpDrC5Q13uu/CC4CX1THUpQuI7uI8Ydcva k2o+xTgKzdFEgPIWWHjB5syCu6YcxPNuoMtgTgSr8t/3dsHeC0ZaCmYkHu4HrW3LWwLw yBBG6eTVMXihHVHIsVWAfwzIDrU4Z26IxsnZWHSLi/V+Ru2sFmPAiCzK20HDcLX+5Rxx 352Y2e6I5teBcfZjhRZALLfVrh/V298TFQ9L8vZZsK611sQ0STPMr2R6MwvKMZbdFS7z GhiA== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp X-Gm-Message-State: AHQUAuYGxPCeQmvtvhTS4FBTWbY8M+ue6/15ZutmIoiOeJdVFDw3R480 rzD32ZN0exx4rw6r5n7SV3BXO19HXV4lcgyjV339TY9TQpMy5Z/RdkSqIT+ExsHwuUVlNWdByRI xBazSVFl2CC6wXTFzmmoS6ubymiI5Sxyvf5pEISBsyehH6ErabPWFS04CFiCZJCBOkA== X-Received: by 2002:aca:e386:: with SMTP id a128mr948516oih.79.1548508271336; Sat, 26 Jan 2019 05:11:11 -0800 (PST) X-Google-Smtp-Source: ALg8bN6fF6GzCwq4I86EVXS8ZV+OGwe0ZbGhvTS1WBl0YAcWtE3sd5ESGJUSR6+Q5uf0ciefspvL X-Received: by 2002:aca:e386:: with SMTP id a128mr948483oih.79.1548508270390; Sat, 26 Jan 2019 05:11:10 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1548508270; cv=none; d=google.com; s=arc-20160816; b=Zc+LtQAIeaPBG4QDaeCo/poFTVYtuITm0UE2jZPd+qf7sig+KTy/ByYP4Q1bt57i8Z aYFEDhqlfQLiNnWYTZXYNdGWwFs4jCEAiSPlsFG03BCg/+ahc7noEPUrB3RZyaJo5aei pk3PdQ0k5jMNFFjaDMScG40FOka05dQntck6u/HKqoUeF/lPu3l9j4T0+ZYCh7FUxK5o PJfwJduqh+IAxf0FtRESexmUY5IhKEbMhnSZvehT5LZB8Mtlc4rB6rLuReW+ZBpZebca uc0KhKHPp9GfNSfI27pkXBCMaGWF3ADpvJB0Xv3H9AT+sVj3+O6I70wgFkdNXnJFdyt5 TfRA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject; bh=Hsx9krwA9P8nQNKjs4bhZ+Iq/VrFfAd1tSDsq96+7Po=; b=YiLGWrA9SMAHGj2iQzxk2ORsXjR62GiX82U4UTWMramGM1PhUiUIDFNTAea7A+AOTN iDi4azGANYzJ55ADjCnbWoymcjMAawwP2mbxdt6lqHupLBWWlkFiQ0cwtDD3KU3FikDP sAbxTF11cAYV+zwxd4T7c+05dgFyf+GAu3Z+1hW5JEZekGJgWdKHFdKJraJURD7RYpSW 5DKLfdMD2EIqCpW/WOaDJbxuq/o8pRN+BXc/BXbEO3wmVvyKFAugj/uQqo+hk0NXzsfS TxgvYiA2n+6qwiDzIOsSBqRRNXyUrlAuBLeInAZCKnJoNPsYyHqV5dd80+ZchI5WHEkH 7Kdw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id q205si2625807oib.203.2019.01.26.05.11.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 26 Jan 2019 05:11:10 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) client-ip=202.181.97.72; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp Received: from fsav110.sakura.ne.jp (fsav110.sakura.ne.jp [27.133.134.237]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x0QDAwU1056613; Sat, 26 Jan 2019 22:10:58 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav110.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav110.sakura.ne.jp); Sat, 26 Jan 2019 22:10:58 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav110.sakura.ne.jp) Received: from [192.168.1.8] (softbank126126163036.bbtec.net [126.126.163.36]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x0QDAqKU056376 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Sat, 26 Jan 2019 22:10:57 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: [PATCH v2] oom, oom_reaper: do not enqueue same task twice To: =?UTF-8?Q?Arkadiusz_Mi=c5=9bkiewicz?= , Andrew Morton Cc: Tejun Heo , cgroups@vger.kernel.org, Aleksa Sarai , Jay Kamat , Roman Gushchin , Michal Hocko , Johannes Weiner , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm References: <20190117122535.njcbqhlmzozdkncw@mikami> <1d36b181-cbaf-6694-1a31-2f7f55d15675@gmail.com> <96ef6615-a5df-30af-b4dc-417a18ca63f1@gmail.com> <1cdbef13-564d-61a6-95f4-579d2cad243d@gmail.com> <20190125163731.GJ50184@devbig004.ftw2.facebook.com> <480296c4-ed7a-3265-e84a-298e42a0f1d5@I-love.SAKURA.ne.jp> <6da6ca69-5a6e-a9f6-d091-f89a8488982a@gmail.com> <72aa8863-a534-b8df-6b9e-f69cf4dd5c4d@i-love.sakura.ne.jp> <33a07810-6dbc-36be-5bb6-a279773ccf69@i-love.sakura.ne.jp> <34e97b46-0792-cc66-e0f2-d72576cdec59@i-love.sakura.ne.jp> <2b0c7d6c-c58a-da7d-6f0a-4900694ec2d3@gmail.com> From: Tetsuo Handa Message-ID: <1d161137-55a5-126f-b47e-b2625bd798ca@i-love.sakura.ne.jp> Date: Sat, 26 Jan 2019 22:10:52 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <2b0c7d6c-c58a-da7d-6f0a-4900694ec2d3@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20190126131052.6gJrKtIQoKnpiLufUmpzm8Mg5-_tM9syO8M-QEw0g7Q@z> On 2019/01/26 20:29, Arkadiusz Miśkiewicz wrote: > On 26/01/2019 12:09, Tetsuo Handa wrote: >> Arkadiusz, will you try this patch? > > > Works. Several tries and always getting 0 pids.current after ~1s. > Thank you for testing. I updated this patch to use tsk->signal->oom_mm (a snapshot of tsk->mm saved by mark_oom_victim(tsk)) rather than raw tsk->mm so that we don't need to worry about possibility of changing tsk->mm across multiple wake_oom_reaper(tsk) calls. >From 9c9e935fc038342c48461aabca666f1b544e32b1 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Sat, 26 Jan 2019 21:57:25 +0900 Subject: [PATCH v2] oom, oom_reaper: do not enqueue same task twice Arkadiusz reported that enabling memcg's group oom killing causes strange memcg statistics where there is no task in a memcg despite the number of tasks in that memcg is not 0. It turned out that there is a bug in wake_oom_reaper() which allows enqueuing same task twice which makes impossible to decrease the number of tasks in that memcg due to a refcount leak. This bug existed since the OOM reaper became invokable from task_will_free_mem(current) path in out_of_memory() in Linux 4.7, but memcg's group oom killing made it easier to trigger this bug by calling wake_oom_reaper() on the same task from one out_of_memory() request. Fix this bug using an approach used by commit 855b018325737f76 ("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task"). As a side effect of this patch, this patch also avoids enqueuing multiple threads sharing memory via task_will_free_mem(current) path. Signed-off-by: Tetsuo Handa Reported-by: Arkadiusz Miśkiewicz Tested-by: Arkadiusz Miśkiewicz Fixes: af8e15cc85a25315 ("oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head") --- mm/oom_kill.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index f0e8cd9..057bfee 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -505,14 +505,6 @@ bool __oom_reap_task_mm(struct mm_struct *mm) struct vm_area_struct *vma; bool ret = true; - /* - * Tell all users of get_user/copy_from_user etc... that the content - * is no longer stable. No barriers really needed because unmapping - * should imply barriers already and the reader would hit a page fault - * if it stumbled over a reaped memory. - */ - set_bit(MMF_UNSTABLE, &mm->flags); - for (vma = mm->mmap ; vma; vma = vma->vm_next) { if (!can_madv_dontneed_vma(vma)) continue; @@ -647,8 +639,13 @@ static int oom_reaper(void *unused) static void wake_oom_reaper(struct task_struct *tsk) { - /* tsk is already queued? */ - if (tsk == oom_reaper_list || tsk->oom_reaper_list) + /* + * Tell all users of get_user/copy_from_user etc... that the content + * is no longer stable. No barriers really needed because unmapping + * should imply barriers already and the reader would hit a page fault + * if it stumbled over a reaped memory. + */ + if (test_and_set_bit(MMF_UNSTABLE, &tsk->signal->oom_mm->flags)) return; get_task_struct(tsk); -- 1.8.3.1