Ming Lei b1a83ee0cb blk-mq: order adding requests to hctx->dispatch and checking SCHED_RESTART ... commit d7d8535f37 upstream. SCHED_RESTART code path is relied to re-run queue for dispatch requests in hctx->dispatch. Meantime the SCHED_RSTART flag is checked when adding requests to hctx->dispatch. memory barriers have to be used for ordering the following two pair of OPs: 1) adding requests to hctx->dispatch and checking SCHED_RESTART in blk_mq_dispatch_rq_list() 2) clearing SCHED_RESTART and checking if there is request in hctx->dispatch in blk_mq_sched_restart(). Without the added memory barrier, either: 1) blk_mq_sched_restart() may miss requests added to hctx->dispatch meantime blk_mq_dispatch_rq_list() observes SCHED_RESTART, and not run queue in dispatch side or 2) blk_mq_dispatch_rq_list still sees SCHED_RESTART, and not run queue in dispatch side, meantime checking if there is request in hctx->dispatch from blk_mq_sched_restart() is missed. IO hang in ltp/fs_fill test is reported by kernel test robot: https://lkml.org/lkml/2020/7/26/77 Turns out it is caused by the above out-of-order OPs. And the IO hang can't be observed any more after applying this patch. Fixes: bd166ef183 ("blk-mq-sched: add framework for MQ capable IO schedulers") Reported-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Christoph Hellwig <hch@lst.de> Cc: David Jeffery <djeffery@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-09-03 11:27:01 +02:00
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partitions
badblocks.c
bfq-cgroup.c	bfq: fix blkio cgroup leakage v4	2020-09-03 11:26:54 +02:00
bfq-iosched.c	block, bfq: turn put_queue into release_process_ref in __bfq_bic_change_cgroup	2020-04-23 10:36:26 +02:00
bfq-iosched.h	bfq: fix blkio cgroup leakage v4	2020-09-03 11:26:54 +02:00
bfq-wf2q.c	bfq: fix blkio cgroup leakage v4	2020-09-03 11:26:54 +02:00
bio-integrity.c	block: release bip in a right way in error path	2020-07-16 08:16:36 +02:00
bio.c	block: Fix page_is_mergeable() for compound pages	2020-09-03 11:26:54 +02:00
blk-cgroup.c	blkcg: fix memleak for iolatency	2020-09-03 11:26:55 +02:00
blk-core.c	Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT"	2020-06-03 08:21:27 +02:00
blk-exec.c
blk-flush.c	blk-mq: insert passthrough request into hctx->dispatch directly	2020-03-21 08:11:52 +01:00
blk-integrity.c
blk-ioc.c	block: Fix use-after-free issue accessing struct io_cq	2020-04-17 10:50:04 +02:00
blk-iocost.c	iocost: Fix check condition of iocg abs_vdebt	2020-08-19 08:15:58 +02:00
blk-iolatency.c
blk-lib.c
blk-map.c
blk-merge.c	block: fix get_max_io_size()	2020-09-03 11:27:01 +02:00
blk-mq-cpumap.c
blk-mq-debugfs-zoned.c
blk-mq-debugfs.c	blk-mq-debugfs: update blk_queue_flag_name[] accordingly for new flags	2020-07-22 09:32:52 +02:00
blk-mq-debugfs.h
blk-mq-pci.c
blk-mq-rdma.c
blk-mq-sched.c	blk-mq: order adding requests to hctx->dispatch and checking SCHED_RESTART	2020-09-03 11:27:01 +02:00
blk-mq-sched.h
blk-mq-sysfs.c
blk-mq-tag.c
blk-mq-tag.h
blk-mq-virtio.c
blk-mq.c	blk-mq: order adding requests to hctx->dispatch and checking SCHED_RESTART	2020-09-03 11:27:01 +02:00
blk-mq.h	blk-mq: insert passthrough request into hctx->dispatch directly	2020-03-21 08:11:52 +01:00
blk-pm.c
blk-pm.h
blk-rq-qos.c
blk-rq-qos.h
blk-settings.c	block: keep bdi->io_pages in sync with max_sectors_kb for stacked devices	2020-04-17 10:50:01 +02:00
blk-softirq.c
blk-stat.c
blk-stat.h
blk-sysfs.c
blk-throttle.c
blk-timeout.c
blk-wbt.c
blk-wbt.h
blk-zoned.c
blk.h
bounce.c
bsg-lib.c
bsg.c
cmdline-parser.c
compat_ioctl.c
elevator.c
genhd.c
ioctl.c
ioprio.c
Kconfig
Kconfig.iosched
kyber-iosched.c
Makefile
mq-deadline.c
opal_proto.h
partition-generic.c
scsi_ioctl.c
sed-opal.c
t10-pi.c