From patchwork Wed Apr 2 04:38:47 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 14035529 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5C09E2F4A for ; Wed, 2 Apr 2025 04:39:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743568786; cv=none; b=fZ/5vcbVayuQVeze29yMuqp2FLrUEZ7YOA+Hj9Tf4gHqWGbZ+qP8CZsBXx4aQT70EpqX+RCk+yOoid7aMydL8QUy64ePoiXspnVXmz8ZtXwvq39QXKfyveP9K61yI0qehR1cKTj87h3xwlpmLszJe/0kzKv0+eJtTNSZ+4y9mMQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743568786; c=relaxed/simple; bh=mw6/Fg6GE7l0Yp/L7bvUaaarqJKD35XZIBiGEBTHp58=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=S2diwMbetea2jTnyqzqP6cSijh49EF2XboP3EaezzvvAuhXEoeOhppvKd+6e6xroJe87bnyssqWX+0znwDwS1H0i9qSipnYOJHmS/29KKfaD2rPqb4lFiwBSUb2BCbDwCttqt17k/TmeaX1dBZN7Xbcagg0XTGnuekPU1G1IFmU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=N7p/tC4B; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="N7p/tC4B" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743568783; 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=nbIIzXCwOjY03btKbmxu74XAzkNBnSudwJ3b1AWeO+U=; b=N7p/tC4Bqq5VnYbQPOS9Jp+0viM6eyVhwFp6AFfYVhT6DDBboq1mq/LiIeJqIu0Z8fNpQo xox1/KajhF0a+yXzYxfVoKf0VUcfgIrwt1j10e5yI04/ha0YAqBEB4Fcs+Uhk2aPUGVGaw U1yNoGvnKADiulQvUP8AEr46RQEGlC8= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-460-_aOB8zU_PK6ZfFRzMXl3AA-1; Wed, 02 Apr 2025 00:39:40 -0400 X-MC-Unique: _aOB8zU_PK6ZfFRzMXl3AA-1 X-Mimecast-MFC-AGG-ID: _aOB8zU_PK6ZfFRzMXl3AA_1743568778 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 295991956080; Wed, 2 Apr 2025 04:39:38 +0000 (UTC) Received: from localhost (unknown [10.72.120.17]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9CF251956094; Wed, 2 Apr 2025 04:39:36 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: =?utf-8?q?Valdis_Kl=C4=93tnieks?= , Nilay Shroff , Christoph Hellwig , Ming Lei Subject: [PATCH 1/3] block: add blk_mq_enter_no_io() and blk_mq_exit_no_io() Date: Wed, 2 Apr 2025 12:38:47 +0800 Message-ID: <20250402043851.946498-2-ming.lei@redhat.com> In-Reply-To: <20250402043851.946498-1-ming.lei@redhat.com> References: <20250402043851.946498-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Add blk_mq_enter_no_io() and blk_mq_exit_no_io() for preventing queue from handling any FS or passthrough IO, meantime the queue is kept in non-freeze state. The added two APIs are for avoiding many potential lock risk related with freeze lock. Also add two variants of memsave version. Signed-off-by: Ming Lei Reviewed-by: Nilay Shroff --- block/blk-core.c | 6 ++++-- block/blk-mq.c | 18 ++++++++++++++++-- block/blk-mq.h | 19 +++++++++++++++++++ block/blk.h | 5 +++-- include/linux/blkdev.h | 8 ++++++++ 5 files changed, 50 insertions(+), 6 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 4623de79effa..a54a18fada8a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -319,7 +319,8 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) smp_rmb(); wait_event(q->mq_freeze_wq, (!q->mq_freeze_depth && - blk_pm_resume_queue(pm, q)) || + (blk_pm_resume_queue(pm, q) || + !blk_queue_no_io(q))) || blk_queue_dying(q)); if (blk_queue_dying(q)) return -ENODEV; @@ -352,7 +353,8 @@ int __bio_queue_enter(struct request_queue *q, struct bio *bio) smp_rmb(); wait_event(q->mq_freeze_wq, (!q->mq_freeze_depth && - blk_pm_resume_queue(false, q)) || + (blk_pm_resume_queue(false, q) || + !blk_queue_no_io(q))) || test_bit(GD_DEAD, &disk->state)); if (test_bit(GD_DEAD, &disk->state)) goto dead; diff --git a/block/blk-mq.c b/block/blk-mq.c index ae8494d88897..075ee51066b3 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -222,8 +222,7 @@ bool __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic) bool unfreeze; mutex_lock(&q->mq_freeze_lock); - if (force_atomic) - q->q_usage_counter.data->force_atomic = true; + q->q_usage_counter.data->force_atomic = force_atomic; q->mq_freeze_depth--; WARN_ON_ONCE(q->mq_freeze_depth < 0); if (!q->mq_freeze_depth) { @@ -278,6 +277,21 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); +void blk_mq_enter_no_io(struct request_queue *q) +{ + blk_mq_freeze_queue_nomemsave(q); + q->no_io = true; + if (__blk_mq_unfreeze_queue(q, true)) + blk_unfreeze_release_lock(q); +} + +void blk_mq_exit_no_io(struct request_queue *q) +{ + blk_mq_freeze_queue_nomemsave(q); + q->no_io = false; + blk_mq_unfreeze_queue_nomemrestore(q); +} + /** * blk_mq_wait_quiesce_done() - wait until in-progress quiesce is done * @set: tag_set to wait on diff --git a/block/blk-mq.h b/block/blk-mq.h index 3011a78cf16a..f49070c8c05f 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -452,4 +452,23 @@ static inline bool blk_mq_can_poll(struct request_queue *q) q->tag_set->map[HCTX_TYPE_POLL].nr_queues; } +void blk_mq_enter_no_io(struct request_queue *q); +void blk_mq_exit_no_io(struct request_queue *q); + +static inline unsigned int __must_check +blk_mq_enter_no_io_memsave(struct request_queue *q) +{ + unsigned int memflags = memalloc_noio_save(); + + blk_mq_enter_no_io(q); + return memflags; +} + +static inline void +blk_mq_exit_no_io_memrestore(struct request_queue *q, unsigned int memflags) +{ + blk_mq_exit_no_io(q); + memalloc_noio_restore(memflags); +} + #endif diff --git a/block/blk.h b/block/blk.h index 006e3be433d2..7d0994c1d3ad 100644 --- a/block/blk.h +++ b/block/blk.h @@ -56,8 +56,9 @@ static inline bool blk_try_enter_queue(struct request_queue *q, bool pm) * The code that increments the pm_only counter must ensure that the * counter is globally visible before the queue is unfrozen. */ - if (blk_queue_pm_only(q) && - (!pm || queue_rpm_status(q) == RPM_SUSPENDED)) + if ((blk_queue_pm_only(q) && + (!pm || queue_rpm_status(q) == RPM_SUSPENDED)) || + blk_queue_no_io(q)) goto fail_put; rcu_read_unlock(); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e39c45bc0a97..1b8fd63eee80 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -498,6 +498,13 @@ struct request_queue { int quiesce_depth; + /* + * Prevent queue from handling IO + * + * keep it in same cache line with q_usage_counter + */ + bool no_io; + struct gendisk *disk; /* @@ -679,6 +686,7 @@ void blk_queue_flag_clear(unsigned int flag, struct request_queue *q); #define blk_queue_sq_sched(q) test_bit(QUEUE_FLAG_SQ_SCHED, &(q)->queue_flags) #define blk_queue_skip_tagset_quiesce(q) \ ((q)->limits.features & BLK_FEAT_SKIP_TAGSET_QUIESCE) +#define blk_queue_no_io(q) (q->no_io) extern void blk_set_pm_only(struct request_queue *q); extern void blk_clear_pm_only(struct request_queue *q); From patchwork Wed Apr 2 04:38:48 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 14035530 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 57DB82F4A for ; 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Wed, 02 Apr 2025 00:39:45 -0400 X-MC-Unique: GU7Cgs1NN2GmKSxtlHebTQ-1 X-Mimecast-MFC-AGG-ID: GU7Cgs1NN2GmKSxtlHebTQ_1743568784 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 67C7E19560BC; Wed, 2 Apr 2025 04:39:44 +0000 (UTC) Received: from localhost (unknown [10.72.120.17]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 128D219560AD; Wed, 2 Apr 2025 04:39:42 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: =?utf-8?q?Valdis_Kl=C4=93tnieks?= , Nilay Shroff , Christoph Hellwig , Ming Lei Subject: [PATCH 2/3] block: don't call freeze queue in elevator_switch() and elevator_disable() Date: Wed, 2 Apr 2025 12:38:48 +0800 Message-ID: <20250402043851.946498-3-ming.lei@redhat.com> In-Reply-To: <20250402043851.946498-1-ming.lei@redhat.com> References: <20250402043851.946498-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Both elevator_switch() and elevator_disable() are called from sysfs store and updating nr_hw_queue code paths only. And in the two code paths, queue has been frozen already, so don't call freeze queue in the two functions. Signed-off-by: Ming Lei Reviewed-by: Nilay Shroff --- block/elevator.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index b4d08026b02c..4d3a8f996c91 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -615,12 +615,10 @@ void elevator_init_mq(struct request_queue *q) */ int elevator_switch(struct request_queue *q, struct elevator_type *new_e) { - unsigned int memflags; int ret; lockdep_assert_held(&q->elevator_lock); - memflags = blk_mq_freeze_queue(q); blk_mq_quiesce_queue(q); if (q->elevator) { @@ -641,7 +639,6 @@ int elevator_switch(struct request_queue *q, struct elevator_type *new_e) out_unfreeze: blk_mq_unquiesce_queue(q); - blk_mq_unfreeze_queue(q, memflags); if (ret) { pr_warn("elv: switch to \"%s\" failed, falling back to \"none\"\n", @@ -653,11 +650,8 @@ int elevator_switch(struct request_queue *q, struct elevator_type *new_e) void elevator_disable(struct request_queue *q) { - unsigned int memflags; - lockdep_assert_held(&q->elevator_lock); 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Wed, 2 Apr 2025 04:39:49 +0000 (UTC) Received: from localhost (unknown [10.72.120.17]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7E56C1800BE2; Wed, 2 Apr 2025 04:39:47 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: =?utf-8?q?Valdis_Kl=C4=93tnieks?= , Nilay Shroff , Christoph Hellwig , Ming Lei , syzbot+4c7e0f9b94ad65811efb@syzkaller.appspotmail.com Subject: [PATCH 3/3] block: use blk_mq_no_io() for avoiding lock dependency Date: Wed, 2 Apr 2025 12:38:49 +0800 Message-ID: <20250402043851.946498-4-ming.lei@redhat.com> In-Reply-To: <20250402043851.946498-1-ming.lei@redhat.com> References: <20250402043851.946498-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Use blk_mq_no_io() to prevent IO from entering queue for avoiding lock dependency between freeze lock and elevator lock, and we have got many such reports: Reported-by: syzbot+4c7e0f9b94ad65811efb@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-block/67e6b425.050a0220.2f068f.007b.GAE@google.com/ Reported-by: Valdis Klētnieks Closes: https://lore.kernel.org/linux-block/7755.1743228130@turing-police/#t Signed-off-by: Ming Lei Reviewed-by: Nilay Shroff --- block/blk-mq.c | 7 ++----- block/blk-sysfs.c | 8 ++++---- block/elevator.c | 4 ++-- 3 files changed, 8 insertions(+), 11 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 075ee51066b3..022d8139910d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4882,9 +4882,6 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) int ret; unsigned long i; - if (WARN_ON_ONCE(!q->mq_freeze_depth)) - return -EINVAL; - if (!set) return -EINVAL; @@ -5025,7 +5022,7 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, memflags = memalloc_noio_save(); list_for_each_entry(q, &set->tag_list, tag_set_list) - blk_mq_freeze_queue_nomemsave(q); + blk_mq_enter_no_io(q); /* * Switch IO scheduler to 'none', cleaning up the data associated @@ -5074,7 +5071,7 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, blk_mq_elv_switch_back(&head, q); list_for_each_entry(q, &set->tag_list, tag_set_list) - blk_mq_unfreeze_queue_nomemrestore(q); + blk_mq_exit_no_io(q); memalloc_noio_restore(memflags); /* Free the excess tags when nr_hw_queues shrink. */ diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index a2882751f0d2..e866875c17be 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -76,7 +76,7 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count) if (ret < 0) return ret; - memflags = blk_mq_freeze_queue(q); + memflags = blk_mq_enter_no_io_memsave(q); mutex_lock(&q->elevator_lock); if (nr < BLKDEV_MIN_RQ) nr = BLKDEV_MIN_RQ; @@ -85,7 +85,7 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count) if (err) ret = err; mutex_unlock(&q->elevator_lock); - blk_mq_unfreeze_queue(q, memflags); + blk_mq_exit_no_io_memrestore(q, memflags); return ret; } @@ -592,7 +592,7 @@ static ssize_t queue_wb_lat_store(struct gendisk *disk, const char *page, if (val < -1) return -EINVAL; - memflags = blk_mq_freeze_queue(q); + memflags = blk_mq_enter_no_io_memsave(q); mutex_lock(&q->elevator_lock); rqos = wbt_rq_qos(q); @@ -623,7 +623,7 @@ static ssize_t queue_wb_lat_store(struct gendisk *disk, const char *page, blk_mq_unquiesce_queue(q); out: mutex_unlock(&q->elevator_lock); - blk_mq_unfreeze_queue(q, memflags); + blk_mq_exit_no_io_memrestore(q, memflags); return ret; } diff --git a/block/elevator.c b/block/elevator.c index 4d3a8f996c91..c9cb8386bf5e 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -724,13 +724,13 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, elv_iosched_load_module(name); - memflags = blk_mq_freeze_queue(q); + memflags = blk_mq_enter_no_io_memsave(q); mutex_lock(&q->elevator_lock); ret = elevator_change(q, name); if (!ret) ret = count; mutex_unlock(&q->elevator_lock); - blk_mq_unfreeze_queue(q, memflags); + blk_mq_exit_no_io_memrestore(q, memflags); return ret; }