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b=BfSRPP9Ex+pPVwS+Qja8scCLs4R9WWSs3LJRXDqoz4N1uEKtpYHKgAWZfN/cHRiAT CWPvgi+rY1vq1HnC1iO89Zzvu2VVFkvutamjL4akHIN8wB/+fdkGa8ChTF/FpnugLT xXN+S4h7tTTZr+VBY5Mc13t1C369RH8udaXhL7nA= Date: Tue, 13 Jan 2026 16:37:39 -0800 From: Andrew Morton To: Jinjiang Tu Cc: , , , , , , , , , , , , Subject: Re: [PATCH v3] mm/mempolicy: fix mpol_rebind_nodemask() for MPOL_F_NUMA_BALANCING Message-Id: <20260113163739.902aade0c1b474723e20de86@linux-foundation.org> In-Reply-To: <25e3d755-4d4d-48c5-b1ac-ff62d37694dd@huawei.com> References: <20251223110523.1161421-1-tujinjiang@huawei.com> <25e3d755-4d4d-48c5-b1ac-ff62d37694dd@huawei.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: mu16ujk637cdx6m3jy9zfdbyewqgz7qm X-Rspamd-Queue-Id: 10FB5180004 X-Rspamd-Server: rspam04 X-HE-Tag: 1768351061-610432 X-HE-Meta: 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 zXzYhvI2 1NEQ/BED5w9o4CBKe5l8j2pOMW0AuMBH2BKqri2MFJtGZIOLKiItahIhc7KF6CbzJzWFRArc8S9bPB8dIV1w2EOWjBHpJ9E8DswlFIDqT0XDKcCuMTl+PHt6sOzHuCCEEoYeKk5axvIN50p0GZ3kENG0wxUORkz6QitHq4frkoDs7coafaAgbPIp8jte58RyP7a/fjqmJdo2IQZt7xjiUDZNzFhbaN5kmUaUTlwfTPhwdCY7SzF4ATqtGq21iS3TAjsE2TkJ9G/GHbBQA8fBieDPVqDzqP/2CCRTDf+Rdk3FFeRUw8zkf7ZdHnaNmPyL6vSzTH8JrnSmsgfFDceEOKY1NfrAtlAB+8Ghcfmszm6XQCDXF7y7BETNU7ZbEgaxv3JQoPQm65fySrPxlbdK47Bkl7slRFnpD/B8rv1SRg+awi5ls3VUcP3LzIPRgf43o3m78UQcnMfkj3vo= 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 Tue, 13 Jan 2026 09:52:42 +0800 Jinjiang Tu wrote: > > 在 2025/12/23 19:05, Jinjiang Tu 写道: > > 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 memory policy. > > > > When the cpuset of tasks changes, the mempolicy of the task is rebound by > > mpol_rebind_nodemask(). When MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES > > are both not set, the behaviour of rebinding should be same whenever > > MPOL_F_NUMA_BALANCING is set or not. So, when an application calls > > set_mempolicy() with MPOL_F_NUMA_BALANCING set but both MPOL_F_STATIC_NODES > > and MPOL_F_RELATIVE_NODES cleared, mempolicy.w.cpuset_mems_allowed should > > be set to cpuset_current_mems_allowed nodemask. However, in current > > implementation, mpol_store_user_nodemask() wrongly returns true, causing > > mempolicy->w.user_nodemask to be incorrectly set to the user-specified > > nodemask. Later, when the cpuset of the application changes, > > mpol_rebind_nodemask() ends up rebinding based on the user-specified > > nodemask rather than the cpuset_mems_allowed nodemask as intended. > > > > To fix this, only set mempolicy->w.user_nodemask to the user-specified > > nodemask if MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES is present. > > > > Fixes: bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes") > > Reviewed-by: Gregory Price > > Reviewed-by: Huang Ying > > Signed-off-by: Jinjiang Tu > > --- > > Change in v3: > > * update changelog > > * collect RB from Huang Ying > > Hi, Andrew > > This patch has been reviewed, could you queue this patch into mm branch? It has been in mm.git since Dec 23 ;) The changelog led me to believe that earlier (-stable) kernels don't need this fix. Maybe that was wrong?