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=-5.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 01440C10F14 for ; Thu, 10 Oct 2019 08:29:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 58B05208C3 for ; Thu, 10 Oct 2019 08:29:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="zRKZvZ6k" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 58B05208C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ED7018E0007; Thu, 10 Oct 2019 04:29:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E5ED78E0003; Thu, 10 Oct 2019 04:29:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D26FC8E0007; Thu, 10 Oct 2019 04:29:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0234.hostedemail.com [216.40.44.234]) by kanga.kvack.org (Postfix) with ESMTP id ADC588E0003 for ; Thu, 10 Oct 2019 04:29:52 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 5349D6D78 for ; Thu, 10 Oct 2019 08:29:52 +0000 (UTC) X-FDA: 76027201824.24.paste09_1bd4bde581334 X-HE-Tag: paste09_1bd4bde581334 X-Filterd-Recvd-Size: 4424 Received: from forwardcorp1o.mail.yandex.net (forwardcorp1o.mail.yandex.net [95.108.205.193]) by imf40.hostedemail.com (Postfix) with ESMTP for ; Thu, 10 Oct 2019 08:29:51 +0000 (UTC) Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1o.mail.yandex.net (Yandex) with ESMTP id D56712E15D0; Thu, 10 Oct 2019 11:29:47 +0300 (MSK) Received: from sas2-62907d92d1d8.qloud-c.yandex.net (sas2-62907d92d1d8.qloud-c.yandex.net [2a02:6b8:c08:b895:0:640:6290:7d92]) by mxbackcorp1g.mail.yandex.net (nwsmtp/Yandex) with ESMTP id Zc688KOaea-TiVmdN0E; Thu, 10 Oct 2019 11:29:47 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1570696187; bh=hLJ/aLE1zH4IN571wxoIu2uw5Z79/QiM5/xU95wGKRY=; h=In-Reply-To:Message-ID:From:Date:References:To:Subject:Cc; b=zRKZvZ6kX56PyRt2T8Xphz93/xAsoc/Env+se02AJ7ZxRyCwDs39GtZgBxTJ3LnbB C1ZCrWUFYh1mpxvzqlPPq0NENg/D/bVtbGrBsW7RPVUAanG26vl+KcQe493DgCThmY 5ve2W5rGVuNS8LPuiiS6f1IoTOLMXZirWNiI8Lks= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:3d4d:a9cb:ef29:4bb1]) by sas2-62907d92d1d8.qloud-c.yandex.net (nwsmtp/Yandex) with ESMTPSA id yLNF14isCU-TiISECQI; Thu, 10 Oct 2019 11:29:44 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: Re: "reuse mergeable anon_vma as parent when fork" causes a crash on s390 To: Wei Yang Cc: Shakeel Butt , Qian Cai , Andrew Morton , Rik van Riel , Linux MM , LKML , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , linux-s390@vger.kernel.org References: <1570656570.5937.24.camel@lca.pw> <20191010023601.GA4793@richard> <20191010031516.GA5060@richard> From: Konstantin Khlebnikov Message-ID: <8e0d9999-9ee3-78e5-2737-5a504243413c@yandex-team.ru> Date: Thu, 10 Oct 2019 11:29:44 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191010031516.GA5060@richard> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-CA Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/10/2019 06.15, Wei Yang wrote: > On Thu, Oct 10, 2019 at 10:36:01AM +0800, Wei Yang wrote: >> Hi, Qian, Shakeel >> >> Thanks for testing. >> >> Sounds I missed some case to handle. anon_vma_clone() now would be called in >> vma_adjust, which is a different case when it is introduced. >> > > Well, I have to correct my statement. The reason is we may did something more > in anon_vma_clone(). > > Here is a quick fix, while I need to go through all the cases carefully. Oops, I've overlooked this case too. You have to check src->anon_vma otherwise in __split_vma or copy_vma dst could pick completely random anon_vma. Also checking prev will not hurt, just to be sure. So, something like this should work: if (!dst->anon_vma && src->anon_vma && prev && pprev && pprev->anon_vma == src->anon_vma) dst->anon_vma = prev->anon_vma; > > diff --git a/mm/rmap.c b/mm/rmap.c > index 12f6c3d7fd9d..2844f442208d 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -271,7 +271,7 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) > * 1. Parent has vm_prev, which implies we have vm_prev. > * 2. Parent and its vm_prev have the same anon_vma. > */ > - if (pprev && pprev->anon_vma == src->anon_vma) > + if (!dst->anon_vma && pprev && pprev->anon_vma == src->anon_vma) > dst->anon_vma = prev->anon_vma; > > list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { > >> BTW, do you have the specific test case? So that I could verify my change. The >> kernel build test doesn't trigger this. >> >> Thanks a lot :-) >> >> On Wed, Oct 09, 2019 at 03:21:11PM -0700, Shakeel Butt wrote: >> -- >> Wei Yang >> Help you, Help me >