From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DF60C433F5 for ; Thu, 14 Oct 2021 08:18:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 177DC61152 for ; Thu, 14 Oct 2021 08:18:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230117AbhJNIUj (ORCPT ); Thu, 14 Oct 2021 04:20:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:34833 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230032AbhJNIUj (ORCPT ); Thu, 14 Oct 2021 04:20:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634199514; 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=g/kvozVUbaeY+snlBIvQUQ6zEskRm3LgqfriGB6wA7o=; b=iXtQVuhWLHXS6NFM5f2xVKtP9ESkHHUOMgmJy/kSlT++Jysb00+0Gp5JJ/pzCEUChbHa61 tGPN3KgmKjm1maknKSvXFMyq8NriMnRy27O108Bnm8uz5QnxIHSA8783N/wk71QZMtuX41 c0GpC6pwR774XDtM9jnG7QQtwg6IxR8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-430-ubuILikANEycPgv86f-wfA-1; Thu, 14 Oct 2021 04:18:30 -0400 X-MC-Unique: ubuILikANEycPgv86f-wfA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 749A51015DA0; Thu, 14 Oct 2021 08:18:29 +0000 (UTC) Received: from localhost (ovpn-8-32.pek2.redhat.com [10.72.8.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id CBE7260936; Thu, 14 Oct 2021 08:18:12 +0000 (UTC) From: Ming Lei To: Jens Axboe , Christoph Hellwig , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Chaitanya Kulkarni Cc: Sagi Grimberg , Keith Busch , Bart Van Assche , Yu Kuai , Ming Lei Subject: [PATCH V4 6/6] blk-mq: support concurrent queue quiesce/unquiesce Date: Thu, 14 Oct 2021 16:17:10 +0800 Message-Id: <20211014081710.1871747-7-ming.lei@redhat.com> In-Reply-To: <20211014081710.1871747-1-ming.lei@redhat.com> References: <20211014081710.1871747-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org blk_mq_quiesce_queue() has been used a bit wide now, so far we don't support concurrent/nested quiesce. One biggest issue is that unquiesce can happen unexpectedly in case that quiesce/unquiesce are run concurrently from more than one context. This patch introduces q->mq_quiesce_depth to deal concurrent quiesce, and we only unquiesce queue when it is the last/outer-most one of all contexts. Several kernel panic issue has been reported[1][2][3] when running stress quiesce test. And this patch has been verified in these reports. [1] https://lore.kernel.org/linux-block/9b21c797-e505-3821-4f5b-df7bf9380328@huawei.com/T/#m1fc52431fad7f33b1ffc3f12c4450e4238540787 [2] https://lore.kernel.org/linux-block/9b21c797-e505-3821-4f5b-df7bf9380328@huawei.com/T/#m10ad90afeb9c8cc318334190a7c24c8b5c5e0722 [3] https://listman.redhat.com/archives/dm-devel/2021-September/msg00189.html Signed-off-by: Ming Lei --- block/blk-mq.c | 22 +++++++++++++++++++--- include/linux/blkdev.h | 2 ++ 2 files changed, 21 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 68cccb2d1f8c..360e8eaee4dc 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -209,7 +209,12 @@ EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue); */ void blk_mq_quiesce_queue_nowait(struct request_queue *q) { - blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q); + unsigned long flags; + + spin_lock_irqsave(&q->queue_lock, flags); + if (!q->quiesce_depth++) + blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q); + spin_unlock_irqrestore(&q->queue_lock, flags); } EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); @@ -250,10 +255,21 @@ EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue); */ void blk_mq_unquiesce_queue(struct request_queue *q) { - blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q); + unsigned long flags; + bool run_queue = false; + + spin_lock_irqsave(&q->queue_lock, flags); + if (WARN_ON_ONCE(q->quiesce_depth <= 0)) { + ; + } else if (!--q->quiesce_depth) { + blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q); + run_queue = true; + } + spin_unlock_irqrestore(&q->queue_lock, flags); /* dispatch requests which are inserted during quiescing */ - blk_mq_run_hw_queues(q, true); + if (run_queue) + blk_mq_run_hw_queues(q, true); } EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 17705c970d7e..52020fae665c 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -314,6 +314,8 @@ struct request_queue { */ struct mutex mq_freeze_lock; + int quiesce_depth; + struct blk_mq_tag_set *tag_set; struct list_head tag_set_list; struct bio_set bio_split; -- 2.31.1