From nobody Sat Oct 4 09:39:45 2025 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 A78BA20C01C; Tue, 19 Aug 2025 01:37:25 +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=1755567447; cv=none; b=u/nIGeXZoBKIH+YuA0r1H/EX3H/pbMVaxksFaQcc1e6PWmcRUItbxbyScnOgqtuyvEZaWhGFFoyAk1yTVCFy0Pwwa5E4gbaKzKSuRibc9/K2gTW5Lj3EZ1ws3LZmMb6jhVSSlesbO2gkWAo5Z4ZksZK0GImjulXIdenyK4vvOv4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755567447; c=relaxed/simple; bh=FSJudYQTSDZW86/RjY87jgMacmrvlS5RP+oQPt2SvGM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RCF23K07HyQfhrDjjdsL+S/U1mY+7tLmSy+APHo/6Cn4FKYV3orsh1W/jOcPIPiI/L5lRX7YZ7Rb9XVGR+bOFxmhiLfTZH6jVIOIykDbNE9hDhsqsPB8nNm/sjvieysUJePT/55dHYTCN1n07sXCy8vLz7/3RWL/LsQ0dFh5ywc= 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 [172.19.93.142]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4c5XJN0QTqzKHMhm; Tue, 19 Aug 2025 09:37:24 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 751511A0359; Tue, 19 Aug 2025 09:37:23 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgA3sxNP1aNouL+mEA--.23100S6; Tue, 19 Aug 2025 09:37:22 +0800 (CST) From: Yu Kuai To: yukuai3@huawei.com, axboe@kernel.dk, bvanassche@acm.org, ming.lei@redhat.com, hare@suse.de, nilay@linux.ibm.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH v2 2/2] blk-mq: fix blk_mq_tags double free while nr_requests grown Date: Tue, 19 Aug 2025 09:29:17 +0800 Message-Id: <20250819012917.523272-3-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250819012917.523272-1-yukuai1@huaweicloud.com> References: <20250819012917.523272-1-yukuai1@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: gCh0CgA3sxNP1aNouL+mEA--.23100S6 X-Coremail-Antispam: 1UD129KBjvJXoW7AF4DGr17tr47Ary8JFy3XFb_yoW8Gr18pF W3Ga1Ykr1agr12yFsrJ347Z345Kw4qqr1FgrsYv345Jr1j9r429r4kWr4IqF40vrs7Canr ZrZFkF98XryDG37anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUm014x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jryl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWU JVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67 kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY 6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0x vEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVj vjDU0xZFpf9x0JUQXo7UUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai In the case user trigger tags grow by queue sysfs attribute nr_requests, hctx->sched_tags will be freed directly and replaced with a new allocated tags, see blk_mq_tag_update_depth(). The problem is that hctx->sched_tags is from elevator->et->tags, while et->tags is still the freed tags, hence later elevator exist will try to free the tags again, causing kernel panic. Fix this problem by replacing et->tags will new allocated tags as well. Noted there are still some long term problems that will require some refactor to be fixed thoroughly[1]. [1] https://lore.kernel.org/all/20250815080216.410665-1-yukuai1@huaweicloud= .com/ Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency = in elv_iosched_store") Signed-off-by: Yu Kuai Reviewed-by: Ming Lei Reviewed-by: Nilay Shroff --- block/blk-mq-tag.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index d880c50629d6..5cffa5668d0c 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -622,6 +622,7 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, return -ENOMEM; =20 blk_mq_free_map_and_rqs(set, *tagsptr, hctx->queue_num); + hctx->queue->elevator->et->tags[hctx->queue_num] =3D new; *tagsptr =3D new; } else { /* --=20 2.39.2