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 04621C433F5 for ; Thu, 6 Jan 2022 15:52:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233007AbiAFPwK (ORCPT ); Thu, 6 Jan 2022 10:52:10 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:53179 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230138AbiAFPwK (ORCPT ); Thu, 6 Jan 2022 10:52:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641484327; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=4t/c2e5dlVL4C0onl5AB0P4i94Iv3cIbHbEUlUanZ+k=; b=ZQnpulol/gORZ0uQ0MgVnbzb0nhJ9PDSR3I7nhniHL+G6j205JudX36v/8NOAbzEkfH0AG fyTDJGV/eehLkfpvpBegaMiCCAwdjz6U/yjpPMpKPVS8ahIh8mBj+Oz9gUYami29PSyIH0 1w08CANC2MisAByFYBZ9b3vNYSR8P/8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-209-eSz1Cuy_NqGuF6pL0zM5gg-1; Thu, 06 Jan 2022 10:52:04 -0500 X-MC-Unique: eSz1Cuy_NqGuF6pL0zM5gg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DF14D1023F4D; Thu, 6 Jan 2022 15:52:02 +0000 (UTC) Received: from T590 (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3D64685EFE; Thu, 6 Jan 2022 15:51:30 +0000 (UTC) Date: Thu, 6 Jan 2022 23:51:25 +0800 From: Ming Lei To: Mike Snitzer Cc: Jens Axboe , linux-block@vger.kernel.org, dm-devel@redhat.com Subject: Re: [PATCH 3/3] dm: mark dm queue as blocking if any underlying is blocking Message-ID: References: <20211221141459.1368176-1-ming.lei@redhat.com> <20211221141459.1368176-4-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jan 06, 2022 at 10:40:51AM -0500, Mike Snitzer wrote: > On Tue, Dec 21 2021 at 9:14P -0500, > Ming Lei wrote: > > > dm request based driver doesn't set BLK_MQ_F_BLOCKING, so dm_queue_rq() > > is supposed to not sleep. > > > > However, blk_insert_cloned_request() is used by dm_queue_rq() for > > queuing underlying request, but the underlying queue may be marked as > > BLK_MQ_F_BLOCKING, so blk_insert_cloned_request() may become to block > > current context, then rcu warning is triggered. > > > > Fixes the issue by marking dm request based queue as BLK_MQ_F_BLOCKING > > if any underlying queue is marked as BLK_MQ_F_BLOCKING, meantime we > > need to allocate srcu beforehand. > > > > Signed-off-by: Ming Lei > > --- > > drivers/md/dm-rq.c | 5 ++++- > > drivers/md/dm-rq.h | 3 ++- > > drivers/md/dm-table.c | 14 ++++++++++++++ > > drivers/md/dm.c | 5 +++-- > > drivers/md/dm.h | 1 + > > 5 files changed, 24 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c > > index 579ab6183d4d..2297d37c62a9 100644 > > --- a/drivers/md/dm-rq.c > > +++ b/drivers/md/dm-rq.c > > @@ -535,7 +535,8 @@ static const struct blk_mq_ops dm_mq_ops = { > > .init_request = dm_mq_init_request, > > }; > > > > -int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) > > +int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t, > > + bool blocking) > > { > > struct dm_target *immutable_tgt; > > int err; > > @@ -550,6 +551,8 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) > > md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING; > > md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues(); > > md->tag_set->driver_data = md; > > + if (blocking) > > + md->tag_set->flags |= BLK_MQ_F_BLOCKING; > > > > md->tag_set->cmd_size = sizeof(struct dm_rq_target_io); > > immutable_tgt = dm_table_get_immutable_target(t); > > As you can see, dm_table_get_immutable_target(t) is called here ^ > > Rather than pass 'blocking' in, please just call dm_table_has_blocking_dev(t); > > But not a big deal, I can clean that up once this gets committed... > > > diff --git a/drivers/md/dm-rq.h b/drivers/md/dm-rq.h > > index 1eea0da641db..5f3729f277d7 100644 > > --- a/drivers/md/dm-rq.h > > +++ b/drivers/md/dm-rq.h > > @@ -30,7 +30,8 @@ struct dm_rq_clone_bio_info { > > struct bio clone; > > }; > > > > -int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t); > > +int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t, > > + bool blocking); > > void dm_mq_cleanup_mapped_device(struct mapped_device *md); > > > > void dm_start_queue(struct request_queue *q); > > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > > index aa173f5bdc3d..e4bdd4f757a3 100644 > > --- a/drivers/md/dm-table.c > > +++ b/drivers/md/dm-table.c > > @@ -1875,6 +1875,20 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t) > > return true; > > } > > > > +/* If the device can block inside ->queue_rq */ > > +static int device_is_io_blocking(struct dm_target *ti, struct dm_dev *dev, > > + sector_t start, sector_t len, void *data) > > +{ > > + struct request_queue *q = bdev_get_queue(dev->bdev); > > + > > + return blk_queue_blocking(q); > > +} > > + > > +bool dm_table_has_blocking_dev(struct dm_table *t) > > +{ > > + return dm_table_any_dev_attr(t, device_is_io_blocking, NULL); > > +} > > + > > static int device_not_nowait_capable(struct dm_target *ti, struct dm_dev *dev, > > sector_t start, sector_t len, void *data) > > { > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > > index 280918cdcabd..2f72877752dd 100644 > > --- a/drivers/md/dm.c > > +++ b/drivers/md/dm.c > > @@ -1761,7 +1761,7 @@ static struct mapped_device *alloc_dev(int minor) > > * established. If request-based table is loaded: blk-mq will > > * override accordingly. > > */ > > - md->disk = blk_alloc_disk(md->numa_node_id); > > + md->disk = blk_alloc_disk_srcu(md->numa_node_id); > > if (!md->disk) > > goto bad; > > md->queue = md->disk->queue; > > @@ -2046,7 +2046,8 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t) > > switch (type) { > > case DM_TYPE_REQUEST_BASED: > > md->disk->fops = &dm_rq_blk_dops; > > - r = dm_mq_init_request_queue(md, t); > > + r = dm_mq_init_request_queue(md, t, > > + dm_table_has_blocking_dev(t)); > > if (r) { > > DMERR("Cannot initialize queue for request-based dm mapped device"); > > return r; > > diff --git a/drivers/md/dm.h b/drivers/md/dm.h > > index 742d9c80efe1..f7f92b272cce 100644 > > --- a/drivers/md/dm.h > > +++ b/drivers/md/dm.h > > @@ -60,6 +60,7 @@ int dm_calculate_queue_limits(struct dm_table *table, > > struct queue_limits *limits); > > int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, > > struct queue_limits *limits); > > +bool dm_table_has_blocking_dev(struct dm_table *t); > > struct list_head *dm_table_get_devices(struct dm_table *t); > > void dm_table_presuspend_targets(struct dm_table *t); > > void dm_table_presuspend_undo_targets(struct dm_table *t); > > -- > > 2.31.1 > > > > Reviewed-by: Mike Snitzer Thanks! > > Late, given holidays we know why, but this patchset is needed for 5.17 > (maybe with added: 'Fixes: 704b914f15fb7 "blk-mq: move srcu from > blk_mq_hw_ctx to request_queue"' to this 3rd patch?) It is one long-term issue, not related with commit 704b914f15fb7. The problem is that rcu read lock is held by blk-mq when running dm_queue_rq() which calls underlying blocking queue's ->queue_rq() which may sleep somewhere. Thanks, Ming 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 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.lore.kernel.org (Postfix) with ESMTPS id 51451C433F5 for ; Thu, 6 Jan 2022 15:52:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641484335; h=from:from:sender:sender:reply-to:subject:subject: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:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=xzWyAPPu2QmXrQ4vbYgKelHdG0HsBwSlk1dBgZtJacs=; b=Rvyw+pzOnWkHz5mLKL3HHuK3KlbF35x5FaIOPT/trifJvi4bltg9mRVoWY3Nrbp8b0ZhB4 hKm72xZTlbRNMUDcGLkn7FGOjStXvtk1WpAN3PPv3GbFC+Zf+MiXr9IEBNxzDkF3p4XiDc 8QcqbVkn3b1UeGGBpxxQG4k+29JBkF4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-578-sG2XW2rpPu6-1dIc51jfKA-1; Thu, 06 Jan 2022 10:52:12 -0500 X-MC-Unique: sG2XW2rpPu6-1dIc51jfKA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DD8031800D50; Thu, 6 Jan 2022 15:52:07 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8160410911BA; Thu, 6 Jan 2022 15:52:07 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 3BFE14BB7C; Thu, 6 Jan 2022 15:52:06 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 206Fq26j000871 for ; Thu, 6 Jan 2022 10:52:02 -0500 Received: by smtp.corp.redhat.com (Postfix) id DDD3885F03; Thu, 6 Jan 2022 15:52:02 +0000 (UTC) Received: from T590 (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3D64685EFE; Thu, 6 Jan 2022 15:51:30 +0000 (UTC) Date: Thu, 6 Jan 2022 23:51:25 +0800 From: Ming Lei To: Mike Snitzer Message-ID: References: <20211221141459.1368176-1-ming.lei@redhat.com> <20211221141459.1368176-4-ming.lei@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-loop: dm-devel@redhat.com Cc: Jens Axboe , linux-block@vger.kernel.org, dm-devel@redhat.com Subject: Re: [dm-devel] [PATCH 3/3] dm: mark dm queue as blocking if any underlying is blocking X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Jan 06, 2022 at 10:40:51AM -0500, Mike Snitzer wrote: > On Tue, Dec 21 2021 at 9:14P -0500, > Ming Lei wrote: > > > dm request based driver doesn't set BLK_MQ_F_BLOCKING, so dm_queue_rq() > > is supposed to not sleep. > > > > However, blk_insert_cloned_request() is used by dm_queue_rq() for > > queuing underlying request, but the underlying queue may be marked as > > BLK_MQ_F_BLOCKING, so blk_insert_cloned_request() may become to block > > current context, then rcu warning is triggered. > > > > Fixes the issue by marking dm request based queue as BLK_MQ_F_BLOCKING > > if any underlying queue is marked as BLK_MQ_F_BLOCKING, meantime we > > need to allocate srcu beforehand. > > > > Signed-off-by: Ming Lei > > --- > > drivers/md/dm-rq.c | 5 ++++- > > drivers/md/dm-rq.h | 3 ++- > > drivers/md/dm-table.c | 14 ++++++++++++++ > > drivers/md/dm.c | 5 +++-- > > drivers/md/dm.h | 1 + > > 5 files changed, 24 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c > > index 579ab6183d4d..2297d37c62a9 100644 > > --- a/drivers/md/dm-rq.c > > +++ b/drivers/md/dm-rq.c > > @@ -535,7 +535,8 @@ static const struct blk_mq_ops dm_mq_ops = { > > .init_request = dm_mq_init_request, > > }; > > > > -int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) > > +int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t, > > + bool blocking) > > { > > struct dm_target *immutable_tgt; > > int err; > > @@ -550,6 +551,8 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) > > md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING; > > md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues(); > > md->tag_set->driver_data = md; > > + if (blocking) > > + md->tag_set->flags |= BLK_MQ_F_BLOCKING; > > > > md->tag_set->cmd_size = sizeof(struct dm_rq_target_io); > > immutable_tgt = dm_table_get_immutable_target(t); > > As you can see, dm_table_get_immutable_target(t) is called here ^ > > Rather than pass 'blocking' in, please just call dm_table_has_blocking_dev(t); > > But not a big deal, I can clean that up once this gets committed... > > > diff --git a/drivers/md/dm-rq.h b/drivers/md/dm-rq.h > > index 1eea0da641db..5f3729f277d7 100644 > > --- a/drivers/md/dm-rq.h > > +++ b/drivers/md/dm-rq.h > > @@ -30,7 +30,8 @@ struct dm_rq_clone_bio_info { > > struct bio clone; > > }; > > > > -int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t); > > +int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t, > > + bool blocking); > > void dm_mq_cleanup_mapped_device(struct mapped_device *md); > > > > void dm_start_queue(struct request_queue *q); > > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > > index aa173f5bdc3d..e4bdd4f757a3 100644 > > --- a/drivers/md/dm-table.c > > +++ b/drivers/md/dm-table.c > > @@ -1875,6 +1875,20 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t) > > return true; > > } > > > > +/* If the device can block inside ->queue_rq */ > > +static int device_is_io_blocking(struct dm_target *ti, struct dm_dev *dev, > > + sector_t start, sector_t len, void *data) > > +{ > > + struct request_queue *q = bdev_get_queue(dev->bdev); > > + > > + return blk_queue_blocking(q); > > +} > > + > > +bool dm_table_has_blocking_dev(struct dm_table *t) > > +{ > > + return dm_table_any_dev_attr(t, device_is_io_blocking, NULL); > > +} > > + > > static int device_not_nowait_capable(struct dm_target *ti, struct dm_dev *dev, > > sector_t start, sector_t len, void *data) > > { > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > > index 280918cdcabd..2f72877752dd 100644 > > --- a/drivers/md/dm.c > > +++ b/drivers/md/dm.c > > @@ -1761,7 +1761,7 @@ static struct mapped_device *alloc_dev(int minor) > > * established. If request-based table is loaded: blk-mq will > > * override accordingly. > > */ > > - md->disk = blk_alloc_disk(md->numa_node_id); > > + md->disk = blk_alloc_disk_srcu(md->numa_node_id); > > if (!md->disk) > > goto bad; > > md->queue = md->disk->queue; > > @@ -2046,7 +2046,8 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t) > > switch (type) { > > case DM_TYPE_REQUEST_BASED: > > md->disk->fops = &dm_rq_blk_dops; > > - r = dm_mq_init_request_queue(md, t); > > + r = dm_mq_init_request_queue(md, t, > > + dm_table_has_blocking_dev(t)); > > if (r) { > > DMERR("Cannot initialize queue for request-based dm mapped device"); > > return r; > > diff --git a/drivers/md/dm.h b/drivers/md/dm.h > > index 742d9c80efe1..f7f92b272cce 100644 > > --- a/drivers/md/dm.h > > +++ b/drivers/md/dm.h > > @@ -60,6 +60,7 @@ int dm_calculate_queue_limits(struct dm_table *table, > > struct queue_limits *limits); > > int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, > > struct queue_limits *limits); > > +bool dm_table_has_blocking_dev(struct dm_table *t); > > struct list_head *dm_table_get_devices(struct dm_table *t); > > void dm_table_presuspend_targets(struct dm_table *t); > > void dm_table_presuspend_undo_targets(struct dm_table *t); > > -- > > 2.31.1 > > > > Reviewed-by: Mike Snitzer Thanks! > > Late, given holidays we know why, but this patchset is needed for 5.17 > (maybe with added: 'Fixes: 704b914f15fb7 "blk-mq: move srcu from > blk_mq_hw_ctx to request_queue"' to this 3rd patch?) It is one long-term issue, not related with commit 704b914f15fb7. The problem is that rcu read lock is held by blk-mq when running dm_queue_rq() which calls underlying blocking queue's ->queue_rq() which may sleep somewhere. Thanks, Ming -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel