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Wed, 4 Nov 2026 09:59:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793786349; bh=3Sob1uMONq6SSsdxxC9IdsMSiFRpVas+YBu0+aDW3Z4=; h=From:Subject:Date:To:Cc:Reply-To; b=ftxirbjqa58cGKoYms+B2+AEZvxmfkOYxeogVZSSXcP0RYRHRPMUxesvr7n4wybyh 4QnHr/4yTVZH4n3qvXvkRsIPCyvGjkBqFGNZuRFbqhidPF/Vv5GuKe7bISZorErXiq OYJyYQ8MnOeh3LEbJM65/j5kCqLYHq8+w/Rm9C1utUJbnDbD56DYbPLUILs7n5jLn8 Sh0P23rRZr+Riol4iQNJUEDLvNgWIxv+zBFZAHQuDwdiiyoFvfnUS0pvFBWAQOUu+N aDPudopCw0QujRlcT7khXfCAZLawyvCWOzxp2yOCletO8c0CRmhPHIHqM0sak503my JY/2exbYfF9QA== Received: from nexus.subspace.kernel.org (localhost [IPv6:::1]) by lkml.kernel.org (Postfix) with ESMTP id 134E746D91; Wed, 4 Nov 2026 09:59:08 +0000 (UTC) From: Daejun Park via B4 Relay Subject: [PATCH 0/2] mm: fix memcg_data reads during a THP split Date: Wed, 04 Nov 2026 18:59:07 +0900 Message-Id: <20261104-kpagecgroup-split-v1-0-f70e947fec85@samsung.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAOsB62oC/x3MQQqAIBRF0a3EHyeYRFlbiQZiL/sUJVoRSHtPG p7BvYkiAiNSXyQKuDnysWdUZUF2MbuD4CmblFRNJZUWqzcO1oXj8iL6jU+hTVt3tgFUC8qdD5j 5+Z/D+L4feHUaV2MAAAA= To: Andrew Morton Cc: Tao Yi , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , David Hildenbrand , Zi Yan , Matthew Wilcox , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Vlastimil Babka , Suren Baghdasaryan , Brendan Jackman , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Daejun Park X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1793786347; l=1142; i=daejun7.park@samsung.com; s=20261006; h=from:subject:message-id; bh=y+BIdTbHzrH+8Uu1YnmKDz/Hk8zUyXmI5VDnrLuv9PY=; b=0+otGc3rNezYaJu/zwXPPYuiIecNe6HZUqy7esh0CFuBqce5P1RDP0GxbRJvib69MJuiM1e+o VoK4dvibbOeC6yGIvA864Y0zKn7FrlYCtd9M/sFikqiNwtBE7itbRNL X-Developer-Key: i=daejun7.park@samsung.com; a=ed25519; pk=4yUfDqGRZTIj0Ik43z1GoMZRWCNm/rgX6uJuM9dtNIg= X-Endpoint-Received: by B4 Relay for daejun7.park@samsung.com/20261006 with auth_id=1122 X-Original-From: Daejun Park Reply-To: daejun7.park@samsung.com Tao Yi reported an oops in page_cgroup_ino() while reading /proc/kpagecgroup and traced it to the THP split in an RFC [1]. The RFC skips frozen folios in the reader. Patch 1 moves the memcg_data copy in the split instead. Patch 2 orders the same loads in page_owner and needs patch 1. Charged large kmalloc pages are frozen, so the RFC would report them as uncharged. My review of the RFC [2] got no reply. Tested on x86_64 with KASAN, see patch 1. [1] https://lore.kernel.org/all/20260907124001.1544655-1-escape@deepseek.com/ [2] https://lore.kernel.org/all/20261028040418epcms2p7ac0f584cdfdc6a0ea9b7f20eadeada3d@epcms2p7/ --- Daejun Park (2): mm/huge_memory: set memcg_data before a split page leaves the folio mm/page_owner: also check PageTail before reading memcg_data mm/huge_memory.c | 17 +++++++++++++---- mm/memcontrol.c | 9 ++++++++- mm/page_owner.c | 7 +++++++ 3 files changed, 28 insertions(+), 5 deletions(-) --- base-commit: a13b500946e5dc467976838572b8ddd2fd777ca7 change-id: 20261028-kpagecgroup-split-8a749c6ee27e Best regards, -- Daejun Park