linux-stable.git/block, branch v4.17.3

blk-mq: reinit q->tag_set_list entry only after grace period

2018-06-25T23:51:26+00:00

commit a347c7ad8edf4c5685154f3fdc3c12fc1db800ba upstream.

It is not allowed to reinit q->tag_set_list list entry while RCU grace
period has not completed yet, otherwise the following soft lockup in
blk_mq_sched_restart() happens:

[ 1064.252652] watchdog: BUG: soft lockup - CPU#12 stuck for 23s! [fio:9270]
[ 1064.254445] task: ffff99b912e8b900 task.stack: ffffa6d54c758000
[ 1064.254613] RIP: 0010:blk_mq_sched_restart+0x96/0x150
[ 1064.256510] Call Trace:
[ 1064.256664]  
[ 1064.256824]  blk_mq_free_request+0xea/0x100
[ 1064.256987]  msg_io_conf+0x59/0xd0 [ibnbd_client]
[ 1064.257175]  complete_rdma_req+0xf2/0x230 [ibtrs_client]
[ 1064.257340]  ? ibtrs_post_recv_empty+0x4d/0x70 [ibtrs_core]
[ 1064.257502]  ibtrs_clt_rdma_done+0xd1/0x1e0 [ibtrs_client]
[ 1064.257669]  ib_create_qp+0x321/0x380 [ib_core]
[ 1064.257841]  ib_process_cq_direct+0xbd/0x120 [ib_core]
[ 1064.258007]  irq_poll_softirq+0xb7/0xe0
[ 1064.258165]  __do_softirq+0x106/0x2a2
[ 1064.258328]  irq_exit+0x92/0xa0
[ 1064.258509]  do_IRQ+0x4a/0xd0
[ 1064.258660]  common_interrupt+0x7a/0x7a
[ 1064.258818]  

Meanwhile another context frees other queue but with the same set of
shared tags:

[ 1288.201183] INFO: task bash:5910 blocked for more than 180 seconds.
[ 1288.201833] bash            D    0  5910   5820 0x00000000
[ 1288.202016] Call Trace:
[ 1288.202315]  schedule+0x32/0x80
[ 1288.202462]  schedule_timeout+0x1e5/0x380
[ 1288.203838]  wait_for_completion+0xb0/0x120
[ 1288.204137]  __wait_rcu_gp+0x125/0x160
[ 1288.204287]  synchronize_sched+0x6e/0x80
[ 1288.204770]  blk_mq_free_queue+0x74/0xe0
[ 1288.204922]  blk_cleanup_queue+0xc7/0x110
[ 1288.205073]  ibnbd_clt_unmap_device+0x1bc/0x280 [ibnbd_client]
[ 1288.205389]  ibnbd_clt_unmap_dev_store+0x169/0x1f0 [ibnbd_client]
[ 1288.205548]  kernfs_fop_write+0x109/0x180
[ 1288.206328]  vfs_write+0xb3/0x1a0
[ 1288.206476]  SyS_write+0x52/0xc0
[ 1288.206624]  do_syscall_64+0x68/0x1d0
[ 1288.206774]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2

What happened is the following:

1. There are several MQ queues with shared tags.
2. One queue is about to be freed and now task is in
   blk_mq_del_queue_tag_set().
3. Other CPU is in blk_mq_sched_restart() and loops over all queues in
   tag list in order to find hctx to restart.

Because linked list entry was modified in blk_mq_del_queue_tag_set()
without proper waiting for a grace period, blk_mq_sched_restart()
never ends, spining in list_for_each_entry_rcu_rr(), thus soft lockup.

Fix is simple: reinit list entry after an RCU grace period elapsed.

Fixes: Fixes: 705cda97ee3a ("blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list")
Cc: stable@vger.kernel.org
Cc: Sagi Grimberg 
Cc: linux-block@vger.kernel.org
Reviewed-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Reviewed-by: Bart Van Assche 
Signed-off-by: Roman Pen 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blkdev_report_zones_ioctl(): Use vmalloc() to allocate large buffers

2018-06-16T07:18:18+00:00

commit 327ea4adcfa37194739f1ec7c70568944d292281 upstream.

Avoid that complaints similar to the following appear in the kernel log
if the number of zones is sufficiently large:

  fio: page allocation failure: order:9, mode:0x140c0c0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null)
  Call Trace:
  dump_stack+0x63/0x88
  warn_alloc+0xf5/0x190
  __alloc_pages_slowpath+0x8f0/0xb0d
  __alloc_pages_nodemask+0x242/0x260
  alloc_pages_current+0x6a/0xb0
  kmalloc_order+0x18/0x50
  kmalloc_order_trace+0x26/0xb0
  __kmalloc+0x20e/0x220
  blkdev_report_zones_ioctl+0xa5/0x1a0
  blkdev_ioctl+0x1ba/0x930
  block_ioctl+0x41/0x50
  do_vfs_ioctl+0xaa/0x610
  SyS_ioctl+0x79/0x90
  do_syscall_64+0x79/0x1b0
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
Signed-off-by: Bart Van Assche 
Cc: Shaun Tancheff 
Cc: Damien Le Moal 
Cc: Christoph Hellwig 
Cc: Martin K. Petersen 
Cc: Hannes Reinecke 
Cc: 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blk-mq: fix sysfs inflight counter

2018-04-26T15:02:01+00:00

When the blk-mq inflight implementation was added, /proc/diskstats was
converted to use it, but /sys/block/$dev/inflight was not. Fix it by
adding another helper to count in-flight requests by data direction.

Fixes: f299b7c7a9de ("blk-mq: provide internal in-flight variant")
Signed-off-by: Omar Sandoval 
Signed-off-by: Jens Axboe

blk-mq: count allocated but not started requests in iostats inflight

2018-04-26T15:02:00+00:00

In the legacy block case, we increment the counter right after we
allocate the request, not when the driver handles it. In both the legacy
and blk-mq cases, part_inc_in_flight() is called from
blk_account_io_start() right after we've allocated the request. blk-mq
only considers requests started requests as inflight, but this is
inconsistent with the legacy definition and the intention in the code.
This removes the started condition and instead counts all allocated
requests.

Fixes: f299b7c7a9de ("blk-mq: provide internal in-flight variant")
Signed-off-by: Omar Sandoval 
Signed-off-by: Jens Axboe

Revert "blk-mq: remove code for dealing with remapping queue"

2018-04-25T15:49:22+00:00

This reverts commit 37c7c6c76d431dd7ef9c29d95f6052bd425f004c.

Turns out some drivers(most are FC drivers) may not use managed
IRQ affinity, and has their customized .map_queues meantime, so
still keep this code for avoiding regression.

Reported-by: Laurence Oberman 
Tested-by: Laurence Oberman 
Tested-by: Christian Borntraeger 
Tested-by: Stefan Haberland 
Cc: Ewan Milne 
Cc: Christoph Hellwig 
Cc: Sagi Grimberg 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

block: mq: Add some minor doc for core structs

2018-04-25T13:58:18+00:00

As it came up in discussion on the mailing list that the semantic
meaning of 'blk_mq_ctx' and 'blk_mq_hw_ctx' isn't completely
obvious to everyone, let's add some minimal kerneldoc for a
starter.

Signed-off-by: Linus Walleij 
Signed-off-by: Jens Axboe

blkcg: init root blkcg_gq under lock

2018-04-19T14:51:59+00:00

The initializing of q->root_blkg is currently outside of queue lock
and rcu, so the blkg may be destroied before the initializing, which
may cause dangling/null references. On the other side, the destroys
of blkg are protected by queue lock or rcu. Put the initializing
inside the queue lock and rcu to make it safer.

Signed-off-by: Jiang Biao 
Signed-off-by: Wen Yang 
CC: Tejun Heo 
CC: Jens Axboe 
Signed-off-by: Jens Axboe

blkcg: small fix on comment in blkcg_init_queue

2018-04-19T14:51:57+00:00

The comment before blkg_create() in blkcg_init_queue() was moved
from blkcg_activate_policy() by commit ec13b1d6f0a0457312e615, but
it does not suit for the new context.

Signed-off-by: Jiang Biao 
Signed-off-by: Wen Yang 
CC: Tejun Heo 
CC: Jens Axboe 
Signed-off-by: Jens Axboe

blkcg: don't hold blkcg lock when deactivating policy

2018-04-18T14:37:18+00:00

As described in the comment of blkcg_activate_policy(),
*Update of each blkg is protected by both queue and blkcg locks so
that holding either lock and testing blkcg_policy_enabled() is
always enough for dereferencing policy data.*
with queue lock held, there is no need to hold blkcg lock in
blkcg_deactivate_policy(). Similar case is in
blkcg_activate_policy(), which has removed holding of blkcg lock in
commit 4c55f4f9ad3001ac1fefdd8d8ca7641d18558e23.

Signed-off-by: Jiang Biao 
Signed-off-by: Wen Yang 
CC: Tejun Heo 
Signed-off-by: Jens Axboe

bfq-iosched: ensure to clear bic/bfqq pointers when preparing request

2018-04-17T23:08:52+00:00

Even if we don't have an IO context attached to a request, we still
need to clear the priv[0..1] pointers, as they could be pointing
to previously used bic/bfqq structures. If we don't do so, we'll
either corrupt memory on dispatching a request, or cause an
imbalance in counters.

Inspired by a fix from Kees.

Reported-by: Oleksandr Natalenko 
Reported-by: Kees Cook 
Cc: stable@vger.kernel.org
Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler")
Signed-off-by: Jens Axboe