From patchwork Wed Dec 18 10:16:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 13913335 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 6DEEA35963 for ; Wed, 18 Dec 2024 10:16:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734516998; cv=none; b=iYPELfMJMNTCYEy82LwZ7rGBp42BeLVKjWMUv4SEk2RySw64MCZF9nJxPdB/XdKz91bstLhgOfH5U28mX/btv1kLbSChI2kwGdXdGm6GI6F+VaPn4jzZ0IT2VzZ9YLj7u8AYRcZQAgeGyHq7N/6TFxzvsOJpjmjIY8xmBY/+ogY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734516998; c=relaxed/simple; bh=rC25hUoRmTEeR27CVTz3LK8dt0A5BjTN4cAoHsTlums=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AIz3xR+Iz4elyuu/ythNuflVNjMRjMHzrmmHSLnkRZ26hTdmZNeeRm29KkkEsbQ3dFjfhpJ4Zayvr+d86KfZQI2OTpQ1nBDx67cMO7wkRZkP5oPKvBerZic7wqDN1Y/7LiQFRe2QUUrR+zZcZvM+AgFU7ukqu5aqv8K1wJVgnZQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=bPqXapoW; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bPqXapoW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734516995; 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: in-reply-to:in-reply-to:references:references; bh=jj8JOuv4V2TlcuoKm0L/7qx24xCzKBAdOEOCt4kxvN4=; b=bPqXapoWliH41BBVB3AL+4FeLwTP6EZ6G0S/D7teYNsh95srLUJ4s0t86a4S6ZQvgGAzm5 tHewX8+ZJ3yGfZVpuMb7VRKGQUn4AX0vEGLYXizZIDbMGbTUvZEzuRdasdupxv/D/QEmDO 0VsYWASd/uea37u/AEsNIwqMQLckvi8= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-632-WdjEmsPPOb-c9mWTkMN_xQ-1; Wed, 18 Dec 2024 05:16:30 -0500 X-MC-Unique: WdjEmsPPOb-c9mWTkMN_xQ-1 X-Mimecast-MFC-AGG-ID: WdjEmsPPOb-c9mWTkMN_xQ Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 80D0A1956088; Wed, 18 Dec 2024 10:16:29 +0000 (UTC) Received: from localhost (unknown [10.72.116.10]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5E44919560AD; Wed, 18 Dec 2024 10:16:27 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: Ming Lei , Nilay Shroff Subject: [PATCH 1/2] block: Revert "block: Fix potential deadlock while freezing queue and acquiring sysfs_lock" Date: Wed, 18 Dec 2024 18:16:14 +0800 Message-ID: <20241218101617.3275704-2-ming.lei@redhat.com> In-Reply-To: <20241218101617.3275704-1-ming.lei@redhat.com> References: <20241218101617.3275704-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 This reverts commit be26ba96421ab0a8fa2055ccf7db7832a13c44d2. Commit be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc") actually reverts commit 22465bbac53c ("blk-mq: move cpuhp callback registering out of q->sysfs_lock"), and causes the original resctrl lockdep warning. So revert it and we need to fix the issue in another way. Cc: Nilay Shroff Fixes: be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc") Signed-off-by: Ming Lei --- block/blk-mq-sysfs.c | 16 ++++++++++------ block/blk-mq.c | 29 +++++++++++------------------ block/blk-sysfs.c | 4 ++-- 3 files changed, 23 insertions(+), 26 deletions(-) diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index cd5ea6eaa76b..156e9bb07abf 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -275,13 +275,15 @@ void blk_mq_sysfs_unregister_hctxs(struct request_queue *q) struct blk_mq_hw_ctx *hctx; unsigned long i; - lockdep_assert_held(&q->sysfs_dir_lock); - + mutex_lock(&q->sysfs_dir_lock); if (!q->mq_sysfs_init_done) - return; + goto unlock; queue_for_each_hw_ctx(q, hctx, i) blk_mq_unregister_hctx(hctx); + +unlock: + mutex_unlock(&q->sysfs_dir_lock); } int blk_mq_sysfs_register_hctxs(struct request_queue *q) @@ -290,10 +292,9 @@ int blk_mq_sysfs_register_hctxs(struct request_queue *q) unsigned long i; int ret = 0; - lockdep_assert_held(&q->sysfs_dir_lock); - + mutex_lock(&q->sysfs_dir_lock); if (!q->mq_sysfs_init_done) - return ret; + goto unlock; queue_for_each_hw_ctx(q, hctx, i) { ret = blk_mq_register_hctx(hctx); @@ -301,5 +302,8 @@ int blk_mq_sysfs_register_hctxs(struct request_queue *q) break; } +unlock: + mutex_unlock(&q->sysfs_dir_lock); + return ret; } diff --git a/block/blk-mq.c b/block/blk-mq.c index 6b6111513986..92e8ddf34575 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4453,8 +4453,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, unsigned long i, j; /* protect against switching io scheduler */ - lockdep_assert_held(&q->sysfs_lock); - + mutex_lock(&q->sysfs_lock); for (i = 0; i < set->nr_hw_queues; i++) { int old_node; int node = blk_mq_get_hctx_node(set, i); @@ -4487,6 +4486,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, xa_for_each_start(&q->hctx_table, j, hctx, j) blk_mq_exit_hctx(q, set, hctx, j); + mutex_unlock(&q->sysfs_lock); /* unregister cpuhp callbacks for exited hctxs */ blk_mq_remove_hw_queues_cpuhp(q); @@ -4518,14 +4518,10 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, xa_init(&q->hctx_table); - mutex_lock(&q->sysfs_lock); - blk_mq_realloc_hw_ctxs(set, q); if (!q->nr_hw_queues) goto err_hctxs; - mutex_unlock(&q->sysfs_lock); - INIT_WORK(&q->timeout_work, blk_mq_timeout_work); blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ); @@ -4544,7 +4540,6 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, return 0; err_hctxs: - mutex_unlock(&q->sysfs_lock); blk_mq_release(q); err_exit: q->mq_ops = NULL; @@ -4925,12 +4920,12 @@ static bool blk_mq_elv_switch_none(struct list_head *head, return false; /* q->elevator needs protection from ->sysfs_lock */ - lockdep_assert_held(&q->sysfs_lock); + mutex_lock(&q->sysfs_lock); /* the check has to be done with holding sysfs_lock */ if (!q->elevator) { kfree(qe); - goto out; + goto unlock; } INIT_LIST_HEAD(&qe->node); @@ -4940,7 +4935,9 @@ static bool blk_mq_elv_switch_none(struct list_head *head, __elevator_get(qe->type); list_add(&qe->node, head); elevator_disable(q); -out: +unlock: + mutex_unlock(&q->sysfs_lock); + return true; } @@ -4969,9 +4966,11 @@ static void blk_mq_elv_switch_back(struct list_head *head, list_del(&qe->node); kfree(qe); + mutex_lock(&q->sysfs_lock); elevator_switch(q, t); /* drop the reference acquired in blk_mq_elv_switch_none */ elevator_put(t); + mutex_unlock(&q->sysfs_lock); } static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, @@ -4991,11 +4990,8 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues) return; - list_for_each_entry(q, &set->tag_list, tag_set_list) { - mutex_lock(&q->sysfs_dir_lock); - mutex_lock(&q->sysfs_lock); + list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_freeze_queue(q); - } /* * Switch IO scheduler to 'none', cleaning up the data associated * with the previous scheduler. We will switch back once we are done @@ -5051,11 +5047,8 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_elv_switch_back(&head, q); - list_for_each_entry(q, &set->tag_list, tag_set_list) { + list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_unfreeze_queue(q); - mutex_unlock(&q->sysfs_lock); - mutex_unlock(&q->sysfs_dir_lock); - } /* Free the excess tags when nr_hw_queues shrink. */ for (i = set->nr_hw_queues; i < prev_nr_hw_queues; i++) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 64f70c713d2f..767598e719ab 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -706,11 +706,11 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr, if (entry->load_module) entry->load_module(disk, page, length); - mutex_lock(&q->sysfs_lock); blk_mq_freeze_queue(q); + mutex_lock(&q->sysfs_lock); res = entry->store(disk, page, length); - blk_mq_unfreeze_queue(q); mutex_unlock(&q->sysfs_lock); + blk_mq_unfreeze_queue(q); return res; }