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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 9E517CA9EC3 for ; Wed, 30 Oct 2019 02:50:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6DC9F20866 for ; Wed, 30 Oct 2019 02:50:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6DC9F20866 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 1CB776B0003; Tue, 29 Oct 2019 22:50:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 17C796B0006; Tue, 29 Oct 2019 22:50:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 092C86B0007; Tue, 29 Oct 2019 22:50:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0219.hostedemail.com [216.40.44.219]) by kanga.kvack.org (Postfix) with ESMTP id DB3B96B0003 for ; Tue, 29 Oct 2019 22:50:25 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 65070181AEF31 for ; Wed, 30 Oct 2019 02:50:25 +0000 (UTC) X-FDA: 76098922410.03.voice65_7802c97bab71c X-HE-Tag: voice65_7802c97bab71c X-Filterd-Recvd-Size: 3851 Received: from out4436.biz.mail.alibaba.com (out4436.biz.mail.alibaba.com [47.88.44.36]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Wed, 30 Oct 2019 02:50:24 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07486;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0TgfhIsK_1572403814; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TgfhIsK_1572403814) by smtp.aliyun-inc.com(127.0.0.1); Wed, 30 Oct 2019 10:50:17 +0800 Subject: Re: mbind() breaks its API definition since v5.2 by commit d883544515aa (mm: mempolicy: make the behavior consistent when MPOL_MF_MOVE* and MPOL_MF_STRICT were specified) To: Li Xinhai , linux-mm , akpm , torvalds Cc: Vlastimil Babka , Linux API , Michal Hocko , Hugh Dickins , "linux-kernel@vger.kernel.org" , lixinhai_lxh References: <2019103010274679257634@gmail.com> From: Yang Shi Message-ID: Date: Tue, 29 Oct 2019 19:50:11 -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: <2019103010274679257634@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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 10/29/19 7:27 PM, Li Xinhai wrote: > One change in do_mbind() of this commit has suspicious usage of return = value of > queue_pages_range(), excerpt as below: > > --- > @@ -1243,10 +1265,15 @@ static long do_mbind(unsigned long start, unsig= ned long len, > =C2=A0 if (err) > =C2=A0 goto mpol_out; > =20 > - err =3D queue_pages_range(mm, start, end, nmask, > + ret =3D queue_pages_range(mm, start, end, nmask, > =C2=A0 =C2=A0flags | MPOL_MF_INVERT, &pagelist); > - if (!err) > - err =3D mbind_range(mm, start, end, new); > + > + if (ret < 0) { =C2=A0 =C2=A0 =C2=A0/////// convert to all possible 'r= et' to '-EIO' <<<< > + err =3D -EIO; > + goto up_out; > + } > + > + err =3D mbind_range(mm, start, end, new); > =20 > =C2=A0 if (!err) { > =C2=A0 int nr_failed =3D 0; > --- > > Note that inside=C2=A0queue_pages_range(), the call to=C2=A0walk_page_r= ange() may return > errors from 'test_walk' of 'struct mm_walk_ops', e.g. -EFAULT. Now, tho= se error > codes are no longer reported to user space application. > > From user space, the mbind() call need to reported error, with EFAULT,= as example: > EFAULT > Part or all of the memory range specified by nodemask and maxnode point= s > outside your accessible address space. Or, there was an unmapped hole i= n the > specified memory range specified by addr and len. Thanks for catching this. That commit was aimed to correct the return=20 values for some corner cases in mbind(), but it should not alter the=20 errno for other failure cases, i.e. -EFAULT. Could you please try the below patch (build test only)? diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 4ae967b..99df43a 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1286,7 +1286,7 @@ static long do_mbind(unsigned long start, unsigned=20 long len, =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 flags | MPOL_MF_INVERT, &pagelist); =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (ret < 0) { -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 err =3D -EIO; +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 err =3D ret; =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 goto up_out; =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } > > Please correct me if this is the intended change(and will have updated = API > definition), or something was misunderstood. > > -Xinhai