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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0D90C433F5 for ; Thu, 20 Jan 2022 11:18:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230424AbiATLS2 (ORCPT ); Thu, 20 Jan 2022 06:18:28 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:39116 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229891AbiATLSZ (ORCPT ); Thu, 20 Jan 2022 06:18:25 -0500 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 92BE3218A9; Thu, 20 Jan 2022 11:18:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1642677504; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=d8VO0ro5++eVxYPby3+L4F01fUksoPWmYpmpbS50Btk=; b=nuvuzlBVkYDxr2xgcBnJJiv47ULnPtdRTDJScmiMOA8+bNYz8tWoANqYonVXzt4soCYFrK +/jLJxWE56mdhnq1q+62Zw/5zOjz7ksITJrIeLbJdbhfzzK8wn4/sBB/6KUEnTOf5cj7G4 b1X1qXujMdoGKFuHdMhXOwJAVF1wau4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1642677504; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=d8VO0ro5++eVxYPby3+L4F01fUksoPWmYpmpbS50Btk=; b=o/YDxOoqxKLCyAgRaLIyLdzQLNJAPwzZkHyjn/gD5o0DZnCJU+JSia1+osg7H6mZ385V6a BmCE59UmpQyevtBA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 857CD13E46; Thu, 20 Jan 2022 11:18:24 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id dewfIABF6WFKPwAAMHmgww (envelope-from ); Thu, 20 Jan 2022 11:18:24 +0000 Subject: Re: [PATCH 2/2] block: hold queue lock while iterating in diskstats_show To: Daniel Wagner , linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jens Axboe References: <20220120105248.117025-1-dwagner@suse.de> <20220120105248.117025-3-dwagner@suse.de> From: Hannes Reinecke Message-ID: Date: Thu, 20 Jan 2022 12:18:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20220120105248.117025-3-dwagner@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/20/22 11:52 AM, Daniel Wagner wrote: > 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 " > While this looks good, it seems to have been cut against an earlier branch; the code in question looks different in my copy. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Felix Imendörffer