From patchwork Thu Jan 20 10:52:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Wagner X-Patchwork-Id: 12718513 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B16C3C433FE for ; Thu, 20 Jan 2022 10:53:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229663AbiATKw4 (ORCPT ); Thu, 20 Jan 2022 05:52:56 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:56112 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229617AbiATKwv (ORCPT ); Thu, 20 Jan 2022 05:52:51 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 04F5E1F76A; Thu, 20 Jan 2022 10:52:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1642675970; h=from:from:reply-to: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=BRntaQvQnRRKs8Q9fD7/O4tfQUl0HeggvKHheBBFdio=; b=Jf0HcFw3c8FQJ9zNNyF4FRXtMG7+0rNJptDq3vrBmWZ+F84NcWK8XUmIw5D8t9bF8+fQth +TANA4NuGgPqBUXHxSXZvgcxWPy3AY/oeKBfwhreGufRxswrjnxATGxhuXYVNubMFBBf+i VvIfsTaKcNGLqe81GFPOABe7wIQ5VCs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1642675970; h=from:from:reply-to: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=BRntaQvQnRRKs8Q9fD7/O4tfQUl0HeggvKHheBBFdio=; b=tL9mPxbp8JZLAftheBJd++yhdFkb1xE9PikvgcAJrkLtjfdLB7djCqUPAQ5oP1dPpalfT4 j23ECmKjNRruzPCQ== Received: from adalid.arch.suse.de (adalid.arch.suse.de [10.161.8.13]) by relay2.suse.de (Postfix) with ESMTP id 1B6B7A3B88; Thu, 20 Jan 2022 10:52:44 +0000 (UTC) Received: by adalid.arch.suse.de (Postfix, from userid 17828) id E4DC95192BF8; Thu, 20 Jan 2022 11:52:49 +0100 (CET) From: Daniel Wagner To: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jens Axboe , Hannes Reinecke , Daniel Wagner Subject: [PATCH 2/2] block: hold queue lock while iterating in diskstats_show Date: Thu, 20 Jan 2022 11:52:48 +0100 Message-Id: <20220120105248.117025-3-dwagner@suse.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20220120105248.117025-1-dwagner@suse.de> References: <20220120105248.117025-1-dwagner@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The request queues can be freed while we operate on them. Make sure we hold a reference when using blk_mq_queue_tag_busy_iter. RIP: blk_mq_queue_tag_busy_iter Call Trace: ? blk_mq_hctx_mark_pending ? diskstats_show ? blk_mq_hctx_mark_pending blk_mq_in_flight diskstats_show ? klist_next seq_read proc_reg_read vfs_read ksys_read do_syscall_64 entry_SYSCALL_64_after_hwframe Signed-off-by: Daniel Wagner --- block/genhd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/genhd.c b/block/genhd.c index c9d4386dd177..0e163055a4e6 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1167,10 +1167,13 @@ static int diskstats_show(struct seq_file *seqf, void *v) if (bdev_is_partition(hd) && !bdev_nr_sectors(hd)) continue; part_stat_read_all(hd, &stat); + if (blk_queue_enter(gp->queue, BLK_MQ_REQ_NOWAIT)) + continue; if (queue_is_mq(gp->queue)) inflight = blk_mq_in_flight(gp->queue, hd); else inflight = part_in_flight(hd); + blk_queue_exit(gp->queue); seq_printf(seqf, "%4d %7d %pg " "%lu %lu %lu %u "