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b=uhxelTzCzhhqPTkR7Fp0jW/ihbKHUq+tliWUV8yeYxVhlp5vbLph6KrYHkASHgDZEwIIAZ xubkytoFNCQQYCAw== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 5430413931; Fri, 22 Aug 2025 06:02:09 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id nln2EuEHqGibbwAAD6G6ig (envelope-from ); Fri, 22 Aug 2025 06:02:09 +0000 Message-ID: <00421980-4602-4fe4-9f54-1345a7709d71@suse.de> Date: Fri, 22 Aug 2025 08:02:08 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] blk-mq: fix blk_mq_tags double free while nr_requests grown To: Yu Kuai , yukuai3@huawei.com, axboe@kernel.dk, bvanassche@acm.org, ming.lei@redhat.com, nilay@linux.ibm.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com References: <20250821060612.1729939-1-yukuai1@huaweicloud.com> <20250821060612.1729939-3-yukuai1@huaweicloud.com> Content-Language: en-US From: Hannes Reinecke In-Reply-To: <20250821060612.1729939-3-yukuai1@huaweicloud.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCPT_COUNT_SEVEN(0.00)[11]; MID_RHS_MATCH_FROM(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:mid,suse.de:dkim,suse.de:email,huawei.com:email]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; DKIM_TRACE(0.00)[suse.de:+] X-Spam-Flag: NO X-Spam-Level: X-Rspamd-Queue-Id: B7AE122202 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -4.51 On 8/21/25 08:06, Yu Kuai wrote: > From: Yu Kuai > > In the case user trigger tags grow by queue sysfs attribute nr_requests, > hctx->sched_tags will be freed directly and replaced with a new > allocated tags, see blk_mq_tag_update_depth(). > > The problem is that hctx->sched_tags is from elevator->et->tags, while > et->tags is still the freed tags, hence later elevator exit will try to > free the tags again, causing kernel panic. > > Fix this problem by replacing et->tags with new allocated tags as well. > > Noted there are still some long term problems that will require some > refactor to be fixed thoroughly[1]. > > [1] https://lore.kernel.org/all/20250815080216.410665-1-yukuai1@huaweicloud.com/ > Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency in elv_iosched_store") > > Signed-off-by: Yu Kuai > Reviewed-by: Ming Lei > Reviewed-by: Nilay Shroff > --- > block/blk-mq-tag.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index d880c50629d6..5cffa5668d0c 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -622,6 +622,7 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, > return -ENOMEM; > > blk_mq_free_map_and_rqs(set, *tagsptr, hctx->queue_num); > + hctx->queue->elevator->et->tags[hctx->queue_num] = new; > *tagsptr = new; > } else { > /* Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich