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Tue, 13 Jan 2026 09:49:13 +0800 (CST) Received: from kwepemr500001.china.huawei.com (unknown [7.202.194.229]) by mail.maildlp.com (Postfix) with ESMTPS id 6B07E40363; Tue, 13 Jan 2026 09:52:44 +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; Tue, 13 Jan 2026 09:52:43 +0800 Message-ID: <25e3d755-4d4d-48c5-b1ac-ff62d37694dd@huawei.com> Date: Tue, 13 Jan 2026 09:52:42 +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: , , , , , , , , , , , CC: References: <20251223110523.1161421-1-tujinjiang@huawei.com> From: Jinjiang Tu In-Reply-To: <20251223110523.1161421-1-tujinjiang@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.179] X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To kwepemr500001.china.huawei.com (7.202.194.229) X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8C6721C0005 X-Stat-Signature: 1cemijyq9kj7ikfngybrk3i7q1ecma6m X-HE-Tag: 1768269170-342810 X-HE-Meta: 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 fmveStHL YH+yR7IEANkwz3pcfDYbx83FmZAzf1WZBvr3WZZM2kHUBWEfDqb6q4yvcYC9EZ8pbj4O0Soolg9CBLv2xb0aTn95JQNlLm8+yRomx50kU8CxVNt4= 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 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? > include/uapi/linux/mempolicy.h | 3 +++ > mm/mempolicy.c | 2 +- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h > index 8fbbe613611a..6c962d866e86 100644 > --- a/include/uapi/linux/mempolicy.h > +++ b/include/uapi/linux/mempolicy.h > @@ -39,6 +39,9 @@ enum { > #define MPOL_MODE_FLAGS \ > (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES | MPOL_F_NUMA_BALANCING) > > +/* Whether the nodemask is specified by users */ > +#define MPOL_USER_NODEMASK_FLAGS (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES) > + > /* Flags for get_mempolicy */ > #define MPOL_F_NODE (1<<0) /* return next IL mode instead of node mask */ > #define MPOL_F_ADDR (1<<1) /* look up vma using address */ > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 68a98ba57882..76da50425712 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -365,7 +365,7 @@ static const struct mempolicy_operations { > > static inline int mpol_store_user_nodemask(const struct mempolicy *pol) > { > - return pol->flags & MPOL_MODE_FLAGS; > + return pol->flags & MPOL_USER_NODEMASK_FLAGS; > } > > static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,