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[68.160.176.52]) by smtp.gmail.com with ESMTPSA id bk25sm1675861qkb.13.2022.01.06.07.40.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jan 2022 07:40:52 -0800 (PST) Date: Thu, 6 Jan 2022 10:40:51 -0500 From: Mike Snitzer To: Ming Lei , Jens Axboe Cc: 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: <20211221141459.1368176-4-ming.lei@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 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?) Jens, can you please pick this patchset up for 5.17? Thanks, Mike