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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 39ADBC48BD7 for ; Thu, 27 Jun 2019 10:03:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D1C32083B for ; Thu, 27 Jun 2019 10:03:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726520AbfF0KDc (ORCPT ); Thu, 27 Jun 2019 06:03:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:40002 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726382AbfF0KDc (ORCPT ); Thu, 27 Jun 2019 06:03:32 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 5DE11ABD2; Thu, 27 Jun 2019 10:03:30 +0000 (UTC) Subject: Re: [PATCH] mm/mempolicy: Fix an incorrect rebind node in mpol_rebind_nodemask To: zhong jiang , akpm@linux-foundation.org, osalvador@suse.de, khandual@linux.vnet.ibm.com, mhocko@suse.com, mgorman@techsingularity.net, aarcange@redhat.com Cc: rcampbell@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1558768043-23184-1-git-send-email-zhongjiang@huawei.com> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; prefer-encrypt=mutual; keydata= mQINBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 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xVKRSg3I2m+DUTVqBy7Lixo73hnW69kSjtqCeamY/NSu6LNP+b0wAOKhwz9hBEwEHLp05+mj 5ZFJyfGsOiNUcMoO/17FO4EBxSDP3FDLllpuzlFD7SXkfJaMWYmXIlO0jLzdfwfcnDzBbPwO hBM8hvtsyq8lq8vJOxv6XD6xcTtj5Az8t2JjdUX6SF9hxJpwhBU0wrCoGDkWp4Bbv6jnF7zP Nzftr4l8RuJoywDIiJpdaNpSlXKpj/K6KrnyAI/joYc7 Message-ID: Date: Thu, 27 Jun 2019 11:59:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <1558768043-23184-1-git-send-email-zhongjiang@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/25/19 9:07 AM, zhong jiang wrote: > We bind an different node to different vma, Unluckily, > it will bind different vma to same node by checking the /proc/pid/numa_maps. > Commit 213980c0f23b ("mm, mempolicy: simplify rebinding mempolicies when updating cpusets") > has introduced the issue. when we change memory policy by seting cpuset.mems, > A process will rebind the specified policy more than one times. > if the cpuset_mems_allowed is not equal to user specified nodes. hence the issue will trigger. > Maybe result in the out of memory which allocating memory from same node. OK, how about this instead? mpol_rebind_nodemask() is called for MPOL_BIND and MPOL_INTERLEAVE mempoclicies when the tasks's cpuset's mems_allowed changes. For policies created without MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES, it works by remapping the policy's allowed nodes (stored in v.nodes) using the previous value of mems_allowed (stored in w.cpuset_mems_allowed) as the domain of map and the new mems_allowed (passed as nodes) as the range of the map (see the comment of bitmap_remap() for details). The result of remapping is stored back as policy's nodemask in v.nodes, and the new value of mems_allowed should be stored in w.cpuset_mems_allowed to facilitate the next rebind, if it happens. However, commit 213980c0f23b ("mm, mempolicy: simplify rebinding mempolicies when updating cpusets") introduced a bug where the result of remapping is stored in w.cpuset_mems_allowed instead. Thus, a mempolicy's allowed nodes can evolve in an unexpected way after a series of rebinding due to cpuset mems_allowed changes, possibly binding to a wrong node or a smaller number of nodes which may e.g. overload them. This patch fixes the bug so rebinding again works as intended. > Fixes: 213980c0f23b ("mm, mempolicy: simplify rebinding mempolicies when updating cpusets") > Signed-off-by: zhong jiang (an example of what exactly was the sequence of set_mempolicy and cpuset mems changes with expected wrt actual results would be nice, but I think the above should be fine by itself) Reviewed-by: Vlastimil Babka > --- > mm/mempolicy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index e3ab1d9..a60a3be 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -345,7 +345,7 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes) > else { > nodes_remap(tmp, pol->v.nodes,pol->w.cpuset_mems_allowed, > *nodes); > - pol->w.cpuset_mems_allowed = tmp; > + pol->w.cpuset_mems_allowed = *nodes; > } > > if (nodes_empty(tmp)) >