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[34.82.242.240]) by smtp.gmail.com with ESMTPSA id v3sm659366pfv.186.2020.05.13.18.11.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 May 2020 18:11:13 -0700 (PDT) Date: Thu, 14 May 2020 01:11:10 +0000 From: Satya Tangirala To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Salman Qazi , Jesse Barnes , Christoph Hellwig , Bart Van Assche , Hannes Reinecke Subject: Re: [PATCH V2] block: add blk_io_schedule() for avoiding task hung in sync dio Message-ID: <20200514011110.GA79384@google.com> References: <20200503015422.1123994-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200503015422.1123994-1-ming.lei@redhat.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, May 03, 2020 at 09:54:22AM +0800, Ming Lei wrote: > Sync dio could be big, or may take long time in discard or in case of > IO failure. > > We have prevented task hung in submit_bio_wait() and blk_execute_rq(), > so apply the same trick for prevent task hung from happening in sync dio. > > Add helper of blk_io_schedule() and use io_schedule_timeout() to prevent > task hung warning. > > Cc: Salman Qazi > Cc: Jesse Barnes > Cc: Christoph Hellwig > Cc: Bart Van Assche > Cc: Hannes Reinecke > Signed-off-by: Ming Lei > --- > V2: > - drop helper of blk_default_io_timeout() > > > fs/block_dev.c | 4 ++-- > fs/direct-io.c | 2 +- > fs/iomap/direct-io.c | 2 +- > include/linux/blkdev.h | 12 ++++++++++++ > 4 files changed, 16 insertions(+), 4 deletions(-) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 5eb30a474f6d..3b396f8c967c 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -256,7 +256,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, > break; > if (!(iocb->ki_flags & IOCB_HIPRI) || > !blk_poll(bdev_get_queue(bdev), qc, true)) > - io_schedule(); > + blk_io_schedule(); > } > __set_current_state(TASK_RUNNING); > > @@ -450,7 +450,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) > > if (!(iocb->ki_flags & IOCB_HIPRI) || > !blk_poll(bdev_get_queue(bdev), qc, true)) > - io_schedule(); > + blk_io_schedule(); > } > __set_current_state(TASK_RUNNING); > > diff --git a/fs/direct-io.c b/fs/direct-io.c > index 00b4d15bb811..6d5370eac2a8 100644 > --- a/fs/direct-io.c > +++ b/fs/direct-io.c > @@ -500,7 +500,7 @@ static struct bio *dio_await_one(struct dio *dio) > spin_unlock_irqrestore(&dio->bio_lock, flags); > if (!(dio->iocb->ki_flags & IOCB_HIPRI) || > !blk_poll(dio->bio_disk->queue, dio->bio_cookie, true)) > - io_schedule(); > + blk_io_schedule(); > /* wake up sets us TASK_RUNNING */ > spin_lock_irqsave(&dio->bio_lock, flags); > dio->waiter = NULL; > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index 20dde5aadcdd..fd3bd06fabb6 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -561,7 +561,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > !dio->submit.last_queue || > !blk_poll(dio->submit.last_queue, > dio->submit.cookie, true)) > - io_schedule(); > + blk_io_schedule(); > } > __set_current_state(TASK_RUNNING); > } > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index f00bd4042295..222eb5f32279 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > struct module; > struct scsi_ioctl_command; > @@ -1827,4 +1828,15 @@ static inline void blk_wake_io_task(struct task_struct *waiter) > wake_up_process(waiter); > } > > +static inline void blk_io_schedule(void) > +{ > + /* Prevent hang_check timer from firing at us during very long I/O */ > + unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; > + > + if (timeout) > + io_schedule_timeout(timeout); > + else > + io_schedule(); > +} > + > #endif This won't compile without CONFIG_BLOCK, since this patch includes linux/sched/sysctl.h only inside the #ifdef CONFIG_BLOCK, while blk_io_schedule is declared outside the #ifdef CONFIG_BLOCK, but references sysctl_hung_task_timeout_secs defined in linux/sched/sysctl.h. Afaict, the function isn't needed without CONFIG_BLOCK, so maybe we should move the function into the #ifdef CONFIG_BLOCK too? > -- > 2.25.2 >