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Mon, 22 Dec 2025 11:04:30 +0800 (CST) Received: from kwepemr500001.china.huawei.com (unknown [7.202.194.229]) by mail.maildlp.com (Postfix) with ESMTPS id CBEED40569; Mon, 22 Dec 2025 11:07:32 +0800 (CST) Received: from huawei.com (10.50.85.135) 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; Mon, 22 Dec 2025 11:07:32 +0800 From: Jinjiang Tu To: , , , , , , , , , , , CC: , Subject: [PATCH v2] mm/mempolicy: fix mpol_rebind_nodemask() for MPOL_F_NUMA_BALANCING Date: Mon, 22 Dec 2025 11:04:56 +0800 Message-ID: <20251222030456.2246728-1-tujinjiang@huawei.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.85.135] X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemr500001.china.huawei.com (7.202.194.229) X-Rspamd-Queue-Id: BFDD9C000C X-Stat-Signature: odofk64pnz5y4mjp8j1kjtdipiyec4s9 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1766372857-705969 X-HE-Meta: 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 quIwqA1a EkUSaXBO9N09Dmy9PQuqWp6usm6cuz79VCfmob1noooZISKK/M7mUJdvFFagrIZwheITDNgBTeZz/daAOYu1RbA1zgXJyEn2HafPOpWXvgR5biGypeGBkWsaG8GnKeDM+JmKZcXFCJoXpQqZX7nVBgf40nrKj+WWbAm/huuE+kA8wLiMqyUgv4Z3eXqNN+9Zc4775CoAOs9zdog2SmNWVhn6p0AOy7pBBnrp038Pp54zRRDJLTZ1RVCbP8w/zfm+Fu+aEywGE8BzL6VYCUa9Ogill//kWBD+Tdza0LyBp8a9RO7AP0kibsMvvrH55JN0PZAJuM5KS8JM/MwOHw3AN96g0gSCRPDggXwYTRMQmkLlV1iyym27KphZyjY3bgFmQYFZrS5eU/MgV07GLN/qWvQ/TgTemSzZroXHhfBvZqBhx0a9tUWN2IpVED53WIT0LSw0Qaz37AX7dqLetjN/l54tdRw== 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: 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(). The intended rebinding behavior of MPOL_F_NUMA_BALANCING was the same as when neither MPOL_F_STATIC_NODES nor MPOL_F_RELATIVE_NODES flags are set. However, this commit breaks it. struct mempolicy has a union member as bellow: union { nodemask_t cpuset_mems_allowed; /* relative to these nodes */ nodemask_t user_nodemask; /* nodemask passed by user */ } w; w.cpuset_mems_allowed and w.user_nodemask are both nodemask type and their difference is only what type of nodemask is stored. mpol_set_nodemask() initializes the union like below: static int mpol_set_nodemask(...) { if (mpol_store_user_nodemask(pol)) pol->w.user_nodemask = *nodes; else pol->w.cpuset_mems_allowed = cpuset_current_mems_allowed; } mpol_store_user_nodemask() returns true for MPOL_F_NUMA_BALANCING incorrectly and the union stores user-passed nodemask. Consequently, mpol_rebind_nodemask() ends up rebinding based on the user-passed nodemask rather than the cpuset_mems_allowed nodemask as intended. To fix this, only store the user 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 Signed-off-by: Jinjiang Tu --- Change since v1: * update changelog and comments. * collect RB from Gregory. 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, -- 2.43.0