From mboxrd@z Thu Jan 1 00:00:00 1970 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 ACFBB2C325D; Fri, 15 Aug 2025 08:10:12 +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=1755245414; cv=none; b=kPZgcfha4fEXbb982qdDaUSmJlgyb4CroWfxJm9JxYHSf/k2vslyvuIYqWhJ8xWXJjoOI3UYe9rrRwS0tVToXome5PE79m7LeP+V0W3lPcs/G44P/vt3vbAYF2IgocK/RiQyV6DaZdRY0SYtrAaURrMLyw567hAuyHRUMvlWEDM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755245414; c=relaxed/simple; bh=69KDuGrzUyZNj6ODPR9SX7N9kGmMJpK+24z+Dbca4L0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Wd99uKNEMh43BwPgzTODCF7cG4r7FU4D8Q5zR39W5It9wLjulkEfCD5ZggEXIQ5Obk8YJydD4lVdcBNbTCzbCh/Un4nDn6LEPgsDDVAuXBDFpfOUoxLSKqEpiqaOUFgU6JzD672YR1jULy4BheHQuE7znr6asy5VCyoliDywjS0= 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 4c3FCR4npxzYQv9C; Fri, 15 Aug 2025 16:10:11 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 456251A07BB; Fri, 15 Aug 2025 16:10:10 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgDHjxBc655o+xX_Dg--.53834S12; Fri, 15 Aug 2025 16:10:10 +0800 (CST) From: Yu Kuai To: axboe@kernel.dk, hare@suse.de, nilay@linux.ibm.com, ming.lei@redhat.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH 08/10] blk-mq: fix blk_mq_tags double free while nr_requests grown Date: Fri, 15 Aug 2025 16:02:14 +0800 Message-Id: <20250815080216.410665-9-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250815080216.410665-1-yukuai1@huaweicloud.com> References: <20250815080216.410665-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgDHjxBc655o+xX_Dg--.53834S12 X-Coremail-Antispam: 1UD129KBjvJXoWxur13Xr1ruF1rZFy3Xr1kXwb_yoWrtF1xpF W5Ga1ak3yFqr18Za4UAw47XwnxKw4vgr17GrWft34F9rnrKr4xZF18GF48XFWIyrWkCFsF kr1DJrZ8ZrZ7Xa7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUma14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkE bVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67 AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUCVW8JwCI 42IY6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCw CI42IY6I8E87Iv67AKxVW8JVWxJwCI42IY6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsG vfC2KfnxnUUI43ZEXa7VUbPC7UUUUUU== X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ 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 allocated elevator_tags, also convert blk_mq_update_nr_requests to void since this helper will never fail now. 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 --- block/blk-mq.c | 19 ++++++------------- block/blk-mq.h | 4 +++- block/blk-sysfs.c | 21 ++++++++++++++------- 3 files changed, 23 insertions(+), 21 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 11c8baebb9a0..e9f037a25fe3 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4917,12 +4917,12 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set) } EXPORT_SYMBOL(blk_mq_free_tag_set); -int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) +void blk_mq_update_nr_requests(struct request_queue *q, + struct elevator_tags *et, unsigned int nr) { struct blk_mq_tag_set *set = q->tag_set; struct blk_mq_hw_ctx *hctx; unsigned long i; - int ret = 0; blk_mq_quiesce_queue(q); @@ -4946,24 +4946,17 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) nr - hctx->sched_tags->nr_reserved_tags); } } else { - queue_for_each_hw_ctx(q, hctx, i) { - if (!hctx->tags) - continue; - ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags, - nr); - if (ret) - goto out; - } + blk_mq_free_sched_tags(q->elevator->et, set); + queue_for_each_hw_ctx(q, hctx, i) + hctx->sched_tags = et->tags[i]; + q->elevator->et = et; } q->nr_requests = nr; if (q->elevator && q->elevator->type->ops.depth_updated) q->elevator->type->ops.depth_updated(q); -out: blk_mq_unquiesce_queue(q); - - return ret; } /* diff --git a/block/blk-mq.h b/block/blk-mq.h index 731f4578d9a8..98740f9c204e 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -6,6 +6,7 @@ #include "blk-stat.h" struct blk_mq_tag_set; +struct elevator_tags; struct blk_mq_ctxs { struct kobject kobj; @@ -45,7 +46,8 @@ void blk_mq_submit_bio(struct bio *bio); int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, struct io_comp_batch *iob, unsigned int flags); void blk_mq_exit_queue(struct request_queue *q); -int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr); +void blk_mq_update_nr_requests(struct request_queue *q, + struct elevator_tags *et, unsigned int nr); void blk_mq_wake_waiters(struct request_queue *q); bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *, bool); diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 37eae7927b45..848648456255 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -64,11 +64,12 @@ static ssize_t queue_requests_show(struct gendisk *disk, char *page) static ssize_t queue_requests_store(struct gendisk *disk, const char *page, size_t count) { - unsigned long nr; - int ret, err; - unsigned int memflags; struct request_queue *q = disk->queue; struct blk_mq_tag_set *set = q->tag_set; + struct elevator_tags *et = NULL; + unsigned int memflags; + unsigned long nr; + int ret; ret = queue_var_store(&nr, page, count); if (ret < 0) @@ -90,12 +91,18 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count) goto unlock; } + if (q->elevator && nr > q->elevator->et->nr_requests) { + /* allocate memory before freezing queue to prevent deadlock */ + et = blk_mq_alloc_sched_tags(set, q->nr_hw_queues, nr); + if (!et) { + ret = -ENOMEM; + goto unlock; + } + } + memflags = blk_mq_freeze_queue(q); mutex_lock(&q->elevator_lock); - err = blk_mq_update_nr_requests(disk->queue, nr); - if (err) - ret = err; - + blk_mq_update_nr_requests(disk->queue, et, nr); mutex_unlock(&q->elevator_lock); blk_mq_unfreeze_queue(q, memflags); -- 2.39.2