From nobody Sat Oct 4 19:16:47 2025 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 9A3352750E6; Thu, 14 Aug 2025 03:43:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755143001; cv=none; b=mo4TDCRkRVPwS3jv3V0tP6JoQzio0a6eIsZ8Gs5Y6cX677n3SjD8KD64AQjEFlr1d1j18roxa12ycDLnFoqM9PuqlY+RIYbh9COQvgGX79LsSpXrp1u8SiysLnbkmjFdBYzxdi/EKGhBhKSZuN08uiifnz5fQ/UAnOL054IJn4Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755143001; c=relaxed/simple; bh=Jvoii4nVwMwLtCBE+IEICnuYYTqxC1rF9PACWcI0ppY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mjokNTeVfqJYDVy4W+V8BL4rNFu0CkSOugmW68HKm7oSRjnSaF3v0frcpVa7p+YP62f3OfL7L11glJIBCxu30fJ1k5gr/IrgS0Zp4IcZx2Z/C5Gq5VEkOIJQe5W6m8vq7lMS0zUZweZCwwaQe0/ZLiI6Z4X+68mcmu3c9oMYgok= 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=45.249.212.51 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 dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4c2WKs4GZNzYQv3p; Thu, 14 Aug 2025 11:43:13 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 342551A07BD; Thu, 14 Aug 2025 11:43:12 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgCnIxRKW51ogs93Dg--.15627S12; Thu, 14 Aug 2025 11:43:11 +0800 (CST) From: Yu Kuai To: axboe@kernel.dk, yukuai3@huawei.com, bvanassche@acm.org, nilay@linux.ibm.com, hare@suse.de, ming.lei@redhat.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 08/16] blk-mq: fix blk_mq_tags double free while nr_requests grown Date: Thu, 14 Aug 2025 11:35:14 +0800 Message-Id: <20250814033522.770575-9-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250814033522.770575-1-yukuai1@huaweicloud.com> References: <20250814033522.770575-1-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: gCh0CgCnIxRKW51ogs93Dg--.15627S12 X-Coremail-Antispam: 1UD129KBjvJXoWxur13Xr1DtF47ZFWfXw48Crg_yoW5Gr4xpF W5Wa13K34Fqr1xZFZ2y3y7Xas0gws2qw1xKFs3tryrtr1UKrs7ur48Wr4FqrWIyrWkCFZ2 krZ8GF9rXryqqaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUmS14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkE bVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67 AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUCVW8JwCI 42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF 4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBI daVFxhVjvjDU0xZFpf9x0JUQFxUUUUUU= 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 using new halper blk_mq_alloc_sched_tags() to allocate a new sched_tags. Meanwhile, there is a longterm problem can be fixed as well: If blk_mq_tag_update_depth() succeed for previous hctx, then bitmap depth is updated, however, if following hctx failed, q->nr_requests is not updated and the previous hctx->sched_tags endup bigger than q->nr_requests. Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency = in elv_iosched_store") Fixes: e3a2b3f931f5 ("blk-mq: allow changing of queue depth through sysfs") Signed-off-by: Yu Kuai Reviewed-by: Ming Lei --- block/blk-mq.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index a7d6a20c1524..f1c11f591c27 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4917,6 +4917,23 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set) } EXPORT_SYMBOL(blk_mq_free_tag_set); =20 +static int blk_mq_sched_grow_tags(struct request_queue *q, unsigned int nr) +{ + struct elevator_tags *et =3D + blk_mq_alloc_sched_tags(q->tag_set, q->nr_hw_queues, nr); + struct blk_mq_hw_ctx *hctx; + unsigned long i; + + if (!et) + return -ENOMEM; + + blk_mq_free_sched_tags(q->elevator->et, q->tag_set); + queue_for_each_hw_ctx(q, hctx, i) + hctx->sched_tags =3D et->tags[i]; + q->elevator->et =3D et; + return 0; +} + int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) { struct blk_mq_tag_set *set =3D q->tag_set; @@ -4940,17 +4957,9 @@ int blk_mq_update_nr_requests(struct request_queue *= q, unsigned int nr) sbitmap_queue_resize(&hctx->sched_tags->bitmap_tags, nr - hctx->sched_tags->nr_reserved_tags); } else { - queue_for_each_hw_ctx(q, hctx, i) { - /* - * If we're using an MQ scheduler, just update the - * scheduler queue depth. This is similar to what the - * old code would do. - */ - ret =3D blk_mq_tag_update_depth(hctx, - &hctx->sched_tags, nr); - if (ret) - goto out; - } + ret =3D blk_mq_sched_grow_tags(q, nr); + if (ret) + goto out; } =20 q->nr_requests =3D nr; --=20 2.39.2