linux.git/block, branch v5.4.64

blk-iocost: ioc_pd_free() shouldn't assume irq disabled

2020-09-09T17:12:35+00:00

commit 5aeac7c4b16069aae49005f0a8d4526baa83341b upstream.

ioc_pd_free() grabs irq-safe ioc->lock without ensuring that irq is disabled
when it can be called with irq disabled or enabled. This has a small chance
of causing A-A deadlocks and triggers lockdep splats. Use irqsave operations
instead.

Signed-off-by: Tejun Heo 
Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: ensure bdi->io_pages is always initialized

2020-09-09T17:12:34+00:00

commit de1b0ee490eafdf65fac9eef9925391a8369f2dc upstream.

If a driver leaves the limit settings as the defaults, then we don't
initialize bdi->io_pages. This means that file systems may need to
work around bdi->io_pages == 0, which is somewhat messy.

Initialize the default value just like we do for ->ra_pages.

Cc: stable@vger.kernel.org
Fixes: 9491ae4aade6 ("mm: don't cap request size based on read-ahead setting")
Reported-by: OGAWA Hirofumi 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blk-mq: order adding requests to hctx->dispatch and checking SCHED_RESTART

2020-09-03T09:27:01+00:00

commit d7d8535f377e9ba87edbf7fbbd634ac942f3f54f 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: bd166ef183c2 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Reported-by: kernel test robot 
Signed-off-by: Ming Lei 
Reviewed-by: Christoph Hellwig 
Cc: Bart Van Assche 
Cc: Christoph Hellwig 
Cc: David Jeffery 
Cc: 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: fix get_max_io_size()

2020-09-03T09:27:01+00:00

commit e4b469c66f3cbb81c2e94d31123d7bcdf3c1dabd upstream.

A previous commit aligning splits to physical block sizes inadvertently
modified one return case such that that it now returns 0 length splits
when the number of sectors doesn't exceed the physical offset. This
later hits a BUG in bio_split(). Restore the previous working behavior.

Fixes: 9cc5169cd478b ("block: Improve physical block alignment of split bios")
Reported-by: Eric Deal 
Signed-off-by: Keith Busch 
Cc: Bart Van Assche 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blkcg: fix memleak for iolatency

2020-09-03T09:26:55+00:00

[ Upstream commit 27029b4b18aa5d3b060f0bf2c26dae254132cfce ]

Normally, blkcg_iolatency_exit() will free related memory in iolatency
when cleanup queue. But if blk_throtl_init() return error and queue init
fail, blkcg_iolatency_exit() will not do that for us. Then it cause
memory leak.

Fixes: d70675121546 ("block: introduce blk-iolatency io controller")
Signed-off-by: Yufen Yu 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

blk-mq: insert request not through ->queue_rq into sw/scheduler queue

2020-09-03T09:26:54+00:00

[ Upstream commit db03f88fae8a2c8007caafa70287798817df2875 ]

c616cbee97ae ("blk-mq: punt failed direct issue to dispatch list") supposed
to add request which has been through ->queue_rq() to the hw queue dispatch
list, however it adds request running out of budget or driver tag to hw queue
too. This way basically bypasses request merge, and causes too many request
dispatched to LLD, and system% is unnecessary increased.

Fixes this issue by adding request not through ->queue_rq into sw/scheduler
queue, and this way is safe because no ->queue_rq is called on this request
yet.

High %system can be observed on Azure storvsc device, and even soft lock
is observed. This patch reduces %system during heavy sequential IO,
meantime decreases soft lockup risk.

Fixes: c616cbee97ae ("blk-mq: punt failed direct issue to dispatch list")
Signed-off-by: Ming Lei 
Cc: Christoph Hellwig 
Cc: Bart Van Assche 
Cc: Mike Snitzer 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bfq: fix blkio cgroup leakage v4

2020-09-03T09:26:54+00:00

[ Upstream commit 2de791ab4918969d8108f15238a701968375f235 ]

Changes from v1:
    - update commit description with proper ref-accounting justification

commit db37a34c563b ("block, bfq: get a ref to a group when adding it to a service tree")
introduce leak forbfq_group and blkcg_gq objects because of get/put
imbalance.
In fact whole idea of original commit is wrong because bfq_group entity
can not dissapear under us because it is referenced by child bfq_queue's
entities from here:
 -> bfq_init_entity()
    ->bfqg_and_blkg_get(bfqg);
    ->entity->parent = bfqg->my_entity

 -> bfq_put_queue(bfqq)
    FINAL_PUT
    ->bfqg_and_blkg_put(bfqq_group(bfqq))
    ->kmem_cache_free(bfq_pool, bfqq);

So parent entity can not disappear while child entity is in tree,
and child entities already has proper protection.
This patch revert commit db37a34c563b ("block, bfq: get a ref to a group when adding it to a service tree")

bfq_group leak trace caused by bad commit:
-> blkg_alloc
   -> bfq_pq_alloc
     -> bfqg_get (+1)
->bfq_activate_bfqq
  ->bfq_activate_requeue_entity
    -> __bfq_activate_entity
       ->bfq_get_entity
         ->bfqg_and_blkg_get (+1)  <==== : Note1
->bfq_del_bfqq_busy
  ->bfq_deactivate_entity+0x53/0xc0 [bfq]
    ->__bfq_deactivate_entity+0x1b8/0x210 [bfq]
      -> bfq_forget_entity(is_in_service = true)
	 entity->on_st_or_in_serv = false   <=== :Note2
	 if (is_in_service)
	     return;  ==> do not touch reference
-> blkcg_css_offline
 -> blkcg_destroy_blkgs
  -> blkg_destroy
   -> bfq_pd_offline
    -> __bfq_deactivate_entity
         if (!entity->on_st_or_in_serv) /* true, because (Note2)
		return false;
 -> bfq_pd_free
    -> bfqg_put() (-1, byt bfqg->ref == 2) because of (Note2)
So bfq_group and blkcg_gq  will leak forever, see test-case below.

##TESTCASE_BEGIN:
#!/bin/bash

max_iters=${1:-100}
#prep cgroup mounts
mount -t tmpfs cgroup_root /sys/fs/cgroup
mkdir /sys/fs/cgroup/blkio
mount -t cgroup -o blkio none /sys/fs/cgroup/blkio

# Prepare blkdev
grep blkio /proc/cgroups
truncate -s 1M img
losetup /dev/loop0 img
echo bfq > /sys/block/loop0/queue/scheduler

grep blkio /proc/cgroups
for ((i=0;i /sys/fs/cgroup/blkio/a/cgroup.procs
    dd if=/dev/loop0 bs=4k count=1 of=/dev/null iflag=direct 2> /dev/null
    echo 0 > /sys/fs/cgroup/blkio/cgroup.procs
    rmdir /sys/fs/cgroup/blkio/a
    grep blkio /proc/cgroups
done
##TESTCASE_END:

Fixes: db37a34c563b ("block, bfq: get a ref to a group when adding it to a service tree")
Tested-by: Oleksandr Natalenko 
Signed-off-by: Dmitry Monakhov 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: Fix page_is_mergeable() for compound pages

2020-09-03T09:26:54+00:00

[ Upstream commit d81665198b83e55a28339d1f3e4890ed8a434556 ]

If we pass in an offset which is larger than PAGE_SIZE, then
page_is_mergeable() thinks it's not mergeable with the previous bio_vec,
leading to a large number of bio_vecs being used.  Use a slightly more
obvious test that the two pages are compatible with each other.

Fixes: 52d52d1c98a9 ("block: only allow contiguous page structs in a bio_vec")
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: respect queue limit of max discard segment

2020-09-03T09:26:54+00:00

[ Upstream commit 943b40c832beb71115e38a1c4d99b640b5342738 ]

When queue_max_discard_segments(q) is 1, blk_discard_mergable() will
return false for discard request, then normal request merge is applied.
However, only queue_max_segments() is checked, so max discard segment
limit isn't respected.

Check max discard segment limit in the request merge code for fixing
the issue.

Discard request failure of virtio_blk is fixed.

Fixes: 69840466086d ("block: fix the DISCARD request merge")
Signed-off-by: Ming Lei 
Reviewed-by: Christoph Hellwig 
Cc: Stefano Garzarella 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

iocost: Fix check condition of iocg abs_vdebt

2020-08-19T06:15:58+00:00

[ Upstream commit d9012a59db54442d5b2fcfdfcded35cf566397d3 ]

We shouldn't skip iocg when its abs_vdebt is not zero.

Fixes: 0b80f9866e6b ("iocost: protect iocg->abs_vdebt with iocg->waitq.lock")
Signed-off-by: Chengming Zhou 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin