From nobody Fri Dec 19 18:59:24 2025 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA7FD2D29D0 for ; Tue, 14 Oct 2025 15:28:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760455729; cv=none; b=XPJoyrob6jGpBFfxQ2SSo1zDZ46zp/AAeDnKrdkp06MLcHk/PAjKzgeTc4wnUw+HLJePFgkMRMgiWPZLmSxFan1l5d7wT4dzS+YfGFofY3/1lhTHFkz9ZbJpYj4B9+2yX0uObch6TYvadeOBfFH6YNeatNCSahe5FrgYdbrRFJU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760455729; c=relaxed/simple; bh=sseQkxVw01RGGymMZQnYe0MAonlReqfHRFNRr3ke7iQ=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=OZUc63vaQoSxLiTpySMTCKzOc9d7izStsGTDn/BMnt4q0+u5zCX90nVfESuvnYz1Z+LXLL9CjjJ1+eyMhM/Mr5gE/gJaZdga1B6kawnggXBivSkdQbxI1SYM5pSaMDkrCnJ6QzaP4KhzRgjwd6uh4hSLUQq9lBm6c8J8fVe2sk0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=gN/wTTWG; arc=none smtp.client-ip=95.215.58.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="gN/wTTWG" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1760455715; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=3LfrRntdqnp7+Z8riKYEbqCkp0MkSxiqZIXsXw6PRKU=; b=gN/wTTWGL9N/luOOdsW4j68R1OpjZ71pxwaSmzY8QKH20jAP2ifGFglkGhFL6+YRWzzyRp YzuTakDCxjxTj+eMz/WOaxFF0o370GIkCcjAxMNpXDhJeA0Nlsc3syciZ9KNI5IEZzd4++ BbDLfbsATBqqetEgJ2hse9wRlW17Hzw= From: Hao Ge To: Vlastimil Babka , Alexei Starovoitov , Andrew Morton , Johannes Weiner , Shakeel Butt , Michal Hocko , Roman Gushchin , Muchun Song , Suren Baghdasaryan Cc: Harry Yoo , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Ge Subject: [PATCH v3] slab: Add check for memcg_data != OBJEXTS_ALLOC_FAIL in folio_memcg_kmem Date: Tue, 14 Oct 2025 23:27:51 +0800 Message-Id: <20251014152751.499376-1-hao.ge@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Hao Ge Since OBJEXTS_ALLOC_FAIL and MEMCG_DATA_OBJEXTS currently share the same bit position, we cannot determine whether memcg_data still points to the slabobj_ext vector simply by checking folio->memcg_data & MEMCG_DATA_OBJEXTS. If obj_exts allocation failed, slab->obj_exts is set to OBJEXTS_ALLOC_FAIL, and during the release of the associated folio, the BUG check is triggered because it was mistakenly assumed that a valid folio->memcg_data was not cleared before freeing the folio. So let's check for memcg_data !=3D OBJEXTS_ALLOC_FAIL in folio_memcg_kmem. Fixes: 7612833192d5 ("slab: Reuse first bit for OBJEXTS_ALLOC_FAIL") Suggested-by: Harry Yoo Signed-off-by: Hao Ge --- v3: Simplify the solution, per Harry's suggestion in the v1 comments Add Suggested-by: Harry Yoo --- include/linux/memcontrol.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 873e510d6f8d..7ed15f858dc4 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -534,7 +534,9 @@ static inline struct mem_cgroup *get_mem_cgroup_from_ob= jcg(struct obj_cgroup *ob static inline bool folio_memcg_kmem(struct folio *folio) { VM_BUG_ON_PGFLAGS(PageTail(&folio->page), &folio->page); - VM_BUG_ON_FOLIO(folio->memcg_data & MEMCG_DATA_OBJEXTS, folio); + VM_BUG_ON_FOLIO((folio->memcg_data !=3D OBJEXTS_ALLOC_FAIL) && + (folio->memcg_data & MEMCG_DATA_OBJEXTS), + folio); return folio->memcg_data & MEMCG_DATA_KMEM; } =20 --=20 2.25.1