From nobody Tue Feb 10 03:37:22 2026 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 425E729993A; Mon, 2 Feb 2026 12:42:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770036138; cv=none; b=gK89VaOG1qSB0koQcSXdw9hiZQ/z/Tg11fv5uBx9VrgRLSZiqhdma0Qw5TYFIx9xj5PoACP+n8ryqrrNmYqGtKaiNmawXCztLy9wBTho/SeavPx/0lji5mStiulq0bLM9xNVS4l2YMrUHZ+eF/XMUVo5r5/Kg6+Fsgt3Y1lWcoY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770036138; c=relaxed/simple; bh=pPXfoKrTv2mokooYdfvQVgxnlqZGnTIp35Vo6MQl8lo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=tJL43u+UvjUTCogTb5soeybXuB82slVyLa2da4ZQMQoOSbS6zN9lPQCkzDwEIIRroQwStyvt8E/Po79xCOz0Jew3YgzbsueAntLedLFJV7cWsMPsEQ3ZJBdSMbyBPMBcfXZ2J01y4fT3taFy8HxhQi4+bJA9JbI+ztgq07+t4eM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.198]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4f4R7y1y6MzKHMn2; Mon, 2 Feb 2026 20:41:50 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 7477240578; Mon, 2 Feb 2026 20:42:10 +0800 (CST) Received: from hulk-vt.huawei.com (unknown [10.67.174.121]) by APP1 (Coremail) with SMTP id cCh0CgDXj+WWm4Bpt7ipFw--.14648S4; Mon, 02 Feb 2026 20:42:10 +0800 (CST) From: Chen Ridong To: dev@lankhorst.se, mripard@kernel.org, natalie.vock@gmx.de, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com Cc: cgroups@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com, chenridong@huaweicloud.com Subject: [PATCH -next v2 2/4] cgroup/dmem: avoid rcu warning when unregister region Date: Mon, 2 Feb 2026 12:27:17 +0000 Message-Id: <20260202122719.414466-3-chenridong@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260202122719.414466-1-chenridong@huaweicloud.com> References: <20260202122719.414466-1-chenridong@huaweicloud.com> 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-CM-TRANSID: cCh0CgDXj+WWm4Bpt7ipFw--.14648S4 X-Coremail-Antispam: 1UD129KBjvJXoW7uFyUtw18trWfGrWkArWxCrg_yoW8KF1Dpa 98Ca43Gw4rZr47Za10yayUur95Za1kXw4UC397Gw45JFn7Gw1Yqan7A34YvFy5AFWakw4a vFs0vr12kw48Aw7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUm014x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jryl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWU JVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67 kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY 6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0x vEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVj vjDU0xZFpf9x0JUQXo7UUUUU= X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ Content-Type: text/plain; charset="utf-8" From: Chen Ridong A warnning was detected: WARNING: suspicious RCU usage 6.19.0-rc7-next-20260129+ #1101 Tainted: G O kernel/cgroup/dmem.c:456 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active =3D 2, debug_locks =3D 1 1 lock held by insmod/532: #0: ffffffff85e78b38 (dmemcg_lock){+.+.}-dmem_cgroup_unregister_region+ stack backtrace: CPU: 2 UID: 0 PID: 532 Comm: insmod Tainted: 6.19.0-rc7-next- Tainted: [O]=3DOOT_MODULE Call Trace: dump_stack_lvl+0xb0/0xd0 lockdep_rcu_suspicious+0x151/0x1c0 dmem_cgroup_unregister_region+0x1e2/0x380 ? __pfx_dmem_test_init+0x10/0x10 [dmem_uaf] dmem_test_init+0x65/0xff0 [dmem_uaf] do_one_initcall+0xbb/0x3a0 The macro list_for_each_rcu() must be used within an RCU read-side critical section (between rcu_read_lock() and rcu_read_unlock()). Using it outside that context, as seen in dmem_cgroup_unregister_region(), triggers the lockdep warning because the RCU protection is not guaranteed. Replace list_for_each_rcu() with list_for_each_entry_safe(), which is appropriate for traversal under spinlock protection where nodes may be deleted. Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup") Signed-off-by: Chen Ridong --- kernel/cgroup/dmem.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/kernel/cgroup/dmem.c b/kernel/cgroup/dmem.c index 1f0d6caaf2fb..787b334e0f5d 100644 --- a/kernel/cgroup/dmem.c +++ b/kernel/cgroup/dmem.c @@ -423,7 +423,7 @@ static void dmemcg_free_region(struct kref *ref) */ void dmem_cgroup_unregister_region(struct dmem_cgroup_region *region) { - struct list_head *entry; + struct dmem_cgroup_pool_state *pool, *next; =20 if (!region) return; @@ -433,10 +433,7 @@ void dmem_cgroup_unregister_region(struct dmem_cgroup_= region *region) /* Remove from global region list */ list_del_rcu(®ion->region_node); =20 - list_for_each_rcu(entry, ®ion->pools) { - struct dmem_cgroup_pool_state *pool =3D - container_of(entry, typeof(*pool), region_node); - + list_for_each_entry_safe(pool, next, ®ion->pools, region_node) { list_del_rcu(&pool->css_node); } =20 --=20 2.34.1