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Wed, 11 Nov 2026 12:56:50 +0000 X-Mizu-Trace-ID: b1405ec9a21693fa X-Migadu-Flow: FLOW_OUT From: Hao Li To: vbabka@kernel.org, harry@kernel.org, akpm@linux-foundation.org Cc: cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Li Subject: [PATCH] mm/slab: don't set SLAB_MAY_ACCOUNT for KMALLOC_PARTITION_CACHES Date: Wed, 11 Nov 2026 20:49:10 +0800 Message-ID: <20261111125628.375624-1-hao.li@linux.dev> X-Mailer: git-send-email 2.54.0 X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: i4rjrpdwwawisycasug79h93geq6m1jq X-Rspamd-Server: rspam01 X-Rspam-User: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: 1296C1C0005 X-HE-Tag: 1794401811-434021 X-HE-Meta: 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 Oa0OkDjR U0nqwFq9JeZtqhkrVJzRcdGeFXcgjrXQ6kJ968+8xco9ygUyTs3PimneWOzmtjOQ0Ywcn0t9CG+eh8rr6c6WMzAtpTCAMdR9582lWfr1vcyDFblMatBnavqYU0edzt/jcsulpJX1HTNphv/JqoG9EQercNm0BBbotRNhUrC01xSmhx5tMSIMtmCd757uqSIqnSmJl5LWe5Saa/Ku80GO3u21SYMCOReCIhIPcqVIWad5BSD4ppx0rUVaHJ+41RcDEnzXuWrjOEGEXCPNaYmmrhm4zkA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 An allocation with __GFP_ACCOUNT set (without __GFP_DMA or __GFP_RECLAIMABLE) is redirected to KMALLOC_CGROUP and will never hit KMALLOC_NORMAL or KMALLOC_PARTITION_CACHES. Consequently, neither of these caches requires objcg slots in obj_exts. While KMALLOC_NORMAL already skips setting SLAB_MAY_ACCOUNT, KMALLOC_PARTITION_CACHES still carries it unnecessarily. Extend the check to skip KMALLOC_PARTITION_CACHES as well, saving unnecessary objcg slots in obj_exts. Signed-off-by: Hao Li --- This doesn't seem like a real bug to me, just a small waste of memory, so I didn't add a Fixes tag. --- mm/slab_common.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 2befd24b4d09..f0ea1fa178e7 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1000,16 +1000,18 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type) #endif /* - * If memcg_kmem is enabled and this is a KMALLOC_NORMAL cache and not - * aliased with any other type, make sure it's never merged with any other - * cache. + * If memcg_kmem is enabled and this is a KMALLOC_NORMAL or + * KMALLOC_PARTITION_CACHES cache and not aliased with any other type, + * make sure it's never merged with any other cache. * * In other cases the kmalloc cache may end up being used for a * __GFP_ACCOUNT allocation so mark it as such. The exception is a * KMALLOC_NO_OBJ_EXT cache. */ if (!mem_cgroup_kmem_disabled()) { - if (type == KMALLOC_NORMAL && KMALLOC_RECLAIM != KMALLOC_NORMAL) + if (type >= KMALLOC_PARTITION_START && + type <= KMALLOC_PARTITION_END && + KMALLOC_RECLAIM != KMALLOC_NORMAL) flags |= SLAB_NO_MERGE; else if (!(flags & SLAB_NO_OBJ_EXT)) flags |= SLAB_MAY_ACCOUNT; -- 2.55.0