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Wed, 14 Jan 2026 09:19:50 +0800 (CST) Received: from kwepemr500001.china.huawei.com (unknown [7.202.194.229]) by mail.maildlp.com (Postfix) with ESMTPS id E8FC24056A; Wed, 14 Jan 2026 09:23:11 +0800 (CST) Received: from [10.174.179.179] (10.174.179.179) by kwepemr500001.china.huawei.com (7.202.194.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 14 Jan 2026 09:23:11 +0800 Message-ID: <0863ce26-3fe9-40e8-b6b8-e86ca8ce610c@huawei.com> Date: Wed, 14 Jan 2026 09:23:10 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/mempolicy: fix mpol_rebind_nodemask() for MPOL_F_NUMA_BALANCING To: Andrew Morton CC: , , , , , , , , , , , , References: <20251223110523.1161421-1-tujinjiang@huawei.com> <25e3d755-4d4d-48c5-b1ac-ff62d37694dd@huawei.com> <20260113163739.902aade0c1b474723e20de86@linux-foundation.org> From: Jinjiang Tu In-Reply-To: <20260113163739.902aade0c1b474723e20de86@linux-foundation.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.179] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To kwepemr500001.china.huawei.com (7.202.194.229) X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 090E0A0003 X-Rspam-User: X-Stat-Signature: xbwcm6kwjzrh8i7cgsieokj6irznnkat X-HE-Tag: 1768353796-123280 X-HE-Meta: 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 UIqQJK4m cTN0Qbc5K9I1KU0J1+IXknewo29dcRoB26Cy3VNt7TQbu3k8ih1PqMoXw3AjZUi1AyEfcEk85iECfUP950OF1y8jmE91j++SU3Sp/tD3c5+yJUOI= 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: 在 2026/1/14 8:37, Andrew Morton 写道: > 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 ;) Indeed, I missed the email. Thanks. > > The changelog led me to believe that earlier (-stable) kernels don't > need this fix. Maybe that was wrong? Yes. This only fixes a minor issue. >