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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B61E6E77188 for ; Sat, 4 Jan 2025 13:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FjA/XcjTSFtkMiIGL1mViD853KKavTU9ifMZrEUBqJA=; b=DjQJBC1QPZhvDpzPy9Q5o91/9p k8BoAmrQU7eNRfjoJJEGEOCSgVhZJuEU+K8oA4ecvgH+I+PYfYfYkPZmV2eNdLUv613WkWiI3edSL P02KkRPMcV8CToVNbh5Cs8KRHE7vpMDgv/R2rRItj08FcR6nTebTv+F9Cj+Cyz4w8J93ak7mQXI/e QGJTa106ivr3vKEZbuPOic1ROqa7B+gT3GZmZ1MJzdr0RCjqlQvv4dzvg6k9oGJUB4gIipZ0dgvDZ A/MgdGr6J4n107HzmHcLn7NP840uCEytTJ0ZlYxFgDI6JaoSD4gr3A21It2dCNv2TyJqbUjNEA2+t d2XCB10A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tU4AK-0000000F2jz-1vpu; Sat, 04 Jan 2025 13:26:08 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tU4AE-0000000F2ha-1uUO for linux-nvme@lists.infradead.org; Sat, 04 Jan 2025 13:26:03 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id B99A05C54B5; Sat, 4 Jan 2025 13:25:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5884C4CEDF; Sat, 4 Jan 2025 13:26:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1735997161; bh=2am3FapwRA8t0IL3zu3UkrLfm2C8ws46MF9QDum4EY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ets+EtRsm2yOvtZgSBvtRg44/RkWIIjTwc1QUHKg3FukZWGr5hBbeULLCDiyKvGzj gsePPpSPaHYYgJ5EpCVw++oj2bi844ygJONT4r+UbloUhMaKXGOmW3Ap6KxmLiy09T BFRInbln8ySSDa2eg8FozL/TjJokO/c90u17eueeWGfXCZnsNvpPmzUEFNqk3Dr+Vi cuZDU65qIQuP0XoREtRLc7++Ahe8HTgxQQX/Yb4VX/nGbph6O8Kmt5jjpp7op4GYWS QkUXnf53m9sfXBktIwjpJo16wa59D/PEFB3v2gQ6sD7vk1awUUBdTOjazidEqFIGN8 6qdB3ZkCxJC0A== From: Damien Le Moal To: Jens Axboe , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Christoph Hellwig , Keith Busch , Sagi Grimberg Cc: Ming Lei , Nilay Shroff Subject: [PATCH 2/3] block: Fix __blk_mq_update_nr_hw_queues() queue freeze and limits lock order Date: Sat, 4 Jan 2025 22:25:21 +0900 Message-ID: <20250104132522.247376-3-dlemoal@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250104132522.247376-1-dlemoal@kernel.org> References: <20250104132522.247376-1-dlemoal@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250104_052602_575794_5298712B X-CRM114-Status: GOOD ( 15.71 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org __blk_mq_update_nr_hw_queues() freezes a device queues during operation, which also includes updating the BLK_FEAT_POLL feature flag for the device queues using queue_limits_start_update() and queue_limits_commit_update(). This call order thus creates an invalid ordering of a queue freeze and queue limit locking which can lead to a deadlock when the device driver must issue commands to probe the device when revalidating its limits. Avoid this issue by moving the update of the BLK_FEAT_POLL feature flag out of the main queue remapping loop to the end of __blk_mq_update_nr_hw_queues(), after the device queues have been unfrozen. Fixes: 8023e144f9d6 ("block: move the poll flag to queue_limits") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal --- block/blk-mq.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 8ac19d4ae3c0..1f63067790c8 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -5021,8 +5021,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, fallback: blk_mq_update_queue_map(set); list_for_each_entry(q, &set->tag_list, tag_set_list) { - struct queue_limits lim; - blk_mq_realloc_hw_ctxs(set, q); if (q->nr_hw_queues != set->nr_hw_queues) { @@ -5036,13 +5034,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, set->nr_hw_queues = prev_nr_hw_queues; goto fallback; } - lim = queue_limits_start_update(q); - if (blk_mq_can_poll(set)) - lim.features |= BLK_FEAT_POLL; - else - lim.features &= ~BLK_FEAT_POLL; - if (queue_limits_commit_update(q, &lim) < 0) - pr_warn("updating the poll flag failed\n"); blk_mq_map_swqueue(q); } @@ -5059,6 +5050,22 @@ 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_unfreeze_queue(q); + list_for_each_entry(q, &set->tag_list, tag_set_list) { + struct queue_limits lim; + int ret; + + lim = queue_limits_start_update(q); + if (blk_mq_can_poll(set)) + lim.features |= BLK_FEAT_POLL; + else + lim.features &= ~BLK_FEAT_POLL; + blk_mq_freeze_queue(q); + ret = queue_limits_commit_update(q, &lim); + blk_mq_unfreeze_queue(q); + if (ret < 0) + pr_warn("updating the poll flag failed\n"); + } + /* Free the excess tags when nr_hw_queues shrink. */ for (i = set->nr_hw_queues; i < prev_nr_hw_queues; i++) __blk_mq_free_map_and_rqs(set, i); -- 2.47.1