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,UNPARSEABLE_RELAY 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 2E3EDC10F14 for ; Thu, 18 Apr 2019 16:48:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E836121479 for ; Thu, 18 Apr 2019 16:48:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E836121479 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8B6C76B0007; Thu, 18 Apr 2019 12:48:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 865706B0008; Thu, 18 Apr 2019 12:48:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 77D466B000A; Thu, 18 Apr 2019 12:48:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pl1-f199.google.com (mail-pl1-f199.google.com [209.85.214.199]) by kanga.kvack.org (Postfix) with ESMTP id 3D7136B0007 for ; Thu, 18 Apr 2019 12:48:16 -0400 (EDT) Received: by mail-pl1-f199.google.com with SMTP id b7so164110plb.17 for ; Thu, 18 Apr 2019 09:48:16 -0700 (PDT) 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-transfer-encoding:content-language; bh=7fd//MdsUnuf1kx0gSh/g4qsh6yU8kXSazoNNEO7Dy0=; b=fLW/BnpypWGkeDv0iRzkAL0k2yfJSKLST0n1VgLdL1nAfRIbAuLdBM5ZtrQEvoUfTE XsCOjjh0yueK2zSH/bUmT4RwhEwWSM2ILxggJSUS7HZ6nj+rIGmfntoVGvhWyo7u3eHG iWIBJiThv5wiVZkEykYxDkV74ei+nn7d5cyDY6BCNqdxOwlu/RuNt9z1yqiDLOMUKG7e 9lew9BN9mqpjdDeLeoiYaqgVzoY4CwyC5Sk9KsiQs1zw5p9J84GWhrzDnpUAvJnDn1Zc 5gaSaFWH/AOQ9J5FiviSMMwUqoYC0PYFUP041WOooneW0JxD2DKc8HZDD3ElpywS7GMp zrxg== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.131 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com X-Gm-Message-State: APjAAAUNbOSBAAR67OvkFUa6XTjL4V2IzFYy1NTLSk1m4MpVWtXNSq26 5cznDK2seTJb+y00scC1w5yLACB5oNj4mPYsEvBthtnOBRZFIWgLOCb2pSvbyms8uYl97cBOivX x5Ch15LPRDzpea5wQKz/C86hH4aDuCABPPa05y0MAcfnTaq725yVg1ymEYt+l9bkgUg== X-Received: by 2002:aa7:820c:: with SMTP id k12mr96357576pfi.177.1555606095698; Thu, 18 Apr 2019 09:48:15 -0700 (PDT) X-Google-Smtp-Source: APXvYqyMWp4/yfC9IwC4VNAJ8Bs/lcY0WuvaB5ZGsKTeAPnNS/sTrLz/V9Niq24vgw0bFzfzr0pB X-Received: by 2002:aa7:820c:: with SMTP id k12mr96357503pfi.177.1555606094773; Thu, 18 Apr 2019 09:48:14 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1555606094; cv=none; d=google.com; s=arc-20160816; b=tEIKptNbyUuFacdRQ2mHwR+jw5+vJosux6AVGkY9wyEjdxbHTWvZkeCQQIRKXeHuF1 cdSjOGE+1K+5jLJwJg7W9tzfTiZlwYltW8hDLXLubPhYZQFijDHtrozCUgH4nE+rtqBx NGlcjppgkKdv0rTRnfaNrD9HtkNsfJ9wpiaFFI+FcSX0YQnAiLxIKuc21cLRfBIVqa5l e8/lR8hmqEDEpwsMYwzfoPW1pYYl9GjDj7m4KLRZW55oEWXAaK2aaA8zcalwcpdYEgrK q4Xk3At0ObOf7hkXNYRVtVWpB6+ad9Qh5RYXpdVuEda3Jc2JFFg+Xnvt6h0Hchz2IRma YHSQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-language:content-transfer-encoding:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject; bh=7fd//MdsUnuf1kx0gSh/g4qsh6yU8kXSazoNNEO7Dy0=; b=vkpyAHv7L4bvSwexZ8/lgg4iPo1Mn4UZUn0N/a3wawIUEBG+m+OM8j7b4p2CK1xFhc d1FMhKxYNf4M1he77uOYWw71afbucl1v4NmsSXfo+V64hQwhhDVYXdisjTOK1iUmoAem NwQlXH//wUQ+XC+8rCKFvSl1DupHtysiwuREeRm4EIFC0QzhYYei/uPts0SeYgv/6koC +Tb6uMT09RExkFhFwYse+tEo84kbhcELqZUfKh3u9NdSbzC8jUceHOW2Yc3/4XUFHjsZ Xt263K4AKW4SAuHCe+N3trLQakXZxwQITSC4ONUUaAzLKHs2660iwcg8N6EYtuD/wE+U uHYg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.131 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com. [115.124.30.131]) by mx.google.com with ESMTPS id l191si2715980pfc.213.2019.04.18.09.48.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Apr 2019 09:48:14 -0700 (PDT) Received-SPF: pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.131 as permitted sender) client-ip=115.124.30.131; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.131 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0TPeyfr1_1555606089; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TPeyfr1_1555606089) by smtp.aliyun-inc.com(127.0.0.1); Fri, 19 Apr 2019 00:48:12 +0800 Subject: Re: [PATCH] mm: use mm.arg_lock in get_cmdline() To: Laurent Dufour , Michal Hocko Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Koutny References: <20190418125827.57479-1-ldufour@linux.ibm.com> <20190418130310.GJ6567@dhcp22.suse.cz> <749b8c73-a97d-b568-c0e5-a7bda77090c9@linux.ibm.com> From: Yang Shi Message-ID: Date: Thu, 18 Apr 2019 09:48:09 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <749b8c73-a97d-b568-c0e5-a7bda77090c9@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US 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: On 4/18/19 6:05 AM, Laurent Dufour wrote: > Le 18/04/2019 à 15:03, Michal Hocko a écrit : >> Michal has posted the same patch few days ago >> http://lkml.kernel.org/r/20190417120347.15397-1-mkoutny@suse.com > > Oups, sorry for the noise, I missed it. Yes, Michal already posted a similar patch. Anyway, thanks for catching this. > >> On Thu 18-04-19 14:58:27, Laurent Dufour wrote: >>> The commit 88aa7cc688d4 ("mm: introduce arg_lock to protect >>> arg_start|end >>> and env_start|end in mm_struct") introduce the spinlock arg_lock to >>> protect >>> the arg_* and env_* field of the mm_struct structure. >>> >>> While reading the code, I found that this new spinlock was not used in >>> get_cmdline() to protect access to these fields. >>> >>> Fixing this even if there is no issue reported yet for this. >>> >>> Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect >>> arg_start|end and env_start|end in mm_struct") >>> Cc: Yang Shi >>> Signed-off-by: Laurent Dufour >>> --- >>>   mm/util.c | 4 ++-- >>>   1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/util.c b/mm/util.c >>> index 05a464929b3e..789760c3028b 100644 >>> --- a/mm/util.c >>> +++ b/mm/util.c >>> @@ -758,12 +758,12 @@ int get_cmdline(struct task_struct *task, char >>> *buffer, int buflen) >>>       if (!mm->arg_end) >>>           goto out_mm;    /* Shh! No looking before we're done */ >>>   -    down_read(&mm->mmap_sem); >>> +    spin_lock(&mm->arg_lock); >>>       arg_start = mm->arg_start; >>>       arg_end = mm->arg_end; >>>       env_start = mm->env_start; >>>       env_end = mm->env_end; >>> -    up_read(&mm->mmap_sem); >>> +    spin_unlock(&mm->arg_lock); >>>         len = arg_end - arg_start; >>>   -- >>> 2.21.0 >>