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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c0970f5fcdsm240554285a.29.2025.12.19.11.23.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Dec 2025 11:23:49 -0800 (PST) Date: Fri, 19 Dec 2025 14:23:12 -0500 From: Gregory Price To: Jinjiang Tu Cc: akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, mgorman@suse.de, linux-mm@kvack.org, wangkefeng.wang@huawei.com Subject: Re: [PATCH] mm/mempolicy: fix mpol_rebind_nodemask() for MPOL_F_NUMA_BALANCING Message-ID: References: <20251213082911.1509735-1-tujinjiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251213082911.1509735-1-tujinjiang@huawei.com> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A3A1980008 X-Stat-Signature: swn4f8qiynpg7r3koqyr3trhk13xeyy1 X-HE-Tag: 1766172230-967607 X-HE-Meta: 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 CzpH0jw1 hZ9pK7b4QetKchRXMy1iUkPPqaiAjARMJVVm+4OjV5b/4tRNqdHK97yyJ6RkePbemgwTeqoortvjVFqp08zzIfCnx9wJDvqZO6Ebgp/mvlPkz6Eu/W2Sah8DtJd6S1+krTacrXSQhVSKYERGAZmf/FPT/DXnb5pSmfXk4oilOHqffVg1wnwHlVtiUw3FRLKp45w+caOAhSGet8GCxGclx+DTwmnqEWgYYqgpZCtKhMu+jenIvawFRWhPwqyy7JI5420feYqyycJfI4Tc6P//BvvK9V3H/2cxuuxAUZGx4WWOz323EzbezkU88nTIGmQIQ113n0SEyy3vILccyOaWEbMEQvP9IAwDgq8kkkwLm1PMtCQYDVNxWISfV3SlqX5dBkPdIcJ62vV5LvfbqP3fjExQruw5vgw8GzV8ieFEOkCxkK7BXGQV79TyVhpcLAoGN7Nfnx3YmUG0zelHny8W807aSCmiyHagn7C26HUramv6pDV4= 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: List-Subscribe: List-Unsubscribe: On Sat, Dec 13, 2025 at 04:29:11PM +0800, Jinjiang Tu wrote: > When mempolicy is rebound due to the process moves to a different cpuset > context, or the set of nodes allowed by current cpuset context changes, > mpol_rebind_nodemask() remaps the nodemask according to the old and new > cpuset_mems_allowed by default. So, use mempolicy.w.cpuset_mems_allowed > to store the old nodemask allowed by cpuset. > > MPOL_F_STATIC_NODES suppresses the node remap and intersects the user's > passed nodemask and nodes allowed by new cpuset context. > For MPOL_F_RELATIVE_NODES, the user's passed nodemask means node IDs that > are relative to the set of node IDs allowed by the process's current > cpuset. So, use mempolicy.w.user_nodemask to store the user's passed > nodemask. > > commit bda420b98505 ("numa balancing: migrate on fault among multiple > bound nodes") adds new flag MPOL_F_NUMA_BALANCING to enable NUMA balancing > for MPOL_BIND, the behaviour of rebinding should be same with default > befaviour. However, mpol_store_user_nodemask() returns true for > MPOL_F_NUMA_BALANCING, leading to mempolicy.w.cpuset_mems_allowed stores > the user's passed nodemask instead of cpuset_current_mems_allowed, and > mpol_rebind_nodemask() remaps wrongly. > > Fixes: bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes") > Signed-off-by: Jinjiang Tu Fix looks good. Thank you! With changelog updates discussed in the thread with Andrew: Reviewed-by: Gregory Price ~Gregory