linux-stable.git/block, branch v5.3.16

block: check bi_size overflow before merge

2019-12-13T07:48:35+00:00

[ Upstream commit e3a5d8e386c3fb973fa75f2403622a8f3640ec06 ]

__bio_try_merge_page() may merge a page to bio without bio_full() check
and cause bi_size overflow.

The overflow typically ends up with sd_init_command() warning on zero
segment request with call trace like this:

    ------------[ cut here ]------------
    WARNING: CPU: 2 PID: 1986 at drivers/scsi/scsi_lib.c:1025 scsi_init_io+0x156/0x180
    CPU: 2 PID: 1986 Comm: kworker/2:1H Kdump: loaded Not tainted 5.4.0-rc7 #1
    Workqueue: kblockd blk_mq_run_work_fn
    RIP: 0010:scsi_init_io+0x156/0x180
    RSP: 0018:ffffa11487663bf0 EFLAGS: 00010246
    RAX: 00000000002be0a0 RBX: ffff8e6e9ff30118 RCX: 0000000000000000
    RDX: 00000000ffffffe1 RSI: 0000000000000000 RDI: ffff8e6e9ff30118
    RBP: ffffa11487663c18 R08: ffffa11487663d28 R09: ffff8e6e9ff30150
    R10: 0000000000000001 R11: 0000000000000000 R12: ffff8e6e9ff30000
    R13: 0000000000000001 R14: ffff8e74a1cf1800 R15: ffff8e6e9ff30000
    FS:  0000000000000000(0000) GS:ffff8e6ea7680000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007fff18cf0fe8 CR3: 0000000659f0a001 CR4: 00000000001606e0
    Call Trace:
     sd_init_command+0x326/0xb40 [sd_mod]
     scsi_queue_rq+0x502/0xaa0
     ? blk_mq_get_driver_tag+0xe7/0x120
     blk_mq_dispatch_rq_list+0x256/0x5a0
     ? elv_rb_del+0x24/0x30
     ? deadline_remove_request+0x7b/0xc0
     blk_mq_do_dispatch_sched+0xa3/0x140
     blk_mq_sched_dispatch_requests+0xfb/0x170
     __blk_mq_run_hw_queue+0x81/0x130
     blk_mq_run_work_fn+0x1b/0x20
     process_one_work+0x179/0x390
     worker_thread+0x4f/0x3e0
     kthread+0x105/0x140
     ? max_active_store+0x80/0x80
     ? kthread_bind+0x20/0x20
     ret_from_fork+0x35/0x40
    ---[ end trace f9036abf5af4a4d3 ]---
    blk_update_request: I/O error, dev sdd, sector 2875552 op 0x1:(WRITE) flags 0x0 phys_seg 0 prio class 0
    XFS (sdd1): writeback error on sector 2875552

__bio_try_merge_page() should check the overflow before actually doing
merge.

Fixes: 07173c3ec276c ("block: enable multipage bvecs")
Reviewed-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Jun'ichi Nomura 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block, bfq: deschedule empty bfq_queues not referred by any process

2019-11-24T07:16:59+00:00

commit 478de3380c1c7dbb0f65f545ee0185848413f3fe upstream.

Since commit 3726112ec731 ("block, bfq: re-schedule empty queues if
they deserve I/O plugging"), to prevent the service guarantees of a
bfq_queue from being violated, the bfq_queue may be left busy, i.e.,
scheduled for service, even if empty (see comments in
__bfq_bfqq_expire() for details). But, if no process will send
requests to the bfq_queue any longer, then there is no point in
keeping the bfq_queue scheduled for service.

In addition, keeping the bfq_queue scheduled for service, but with no
process reference any longer, may cause the bfq_queue to be freed when
descheduled from service. But this is assumed to never happen, and
causes a UAF if it happens. This, in turn, caused crashes [1, 2].

This commit fixes this issue by descheduling an empty bfq_queue when
it remains with not process reference.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1767539
[2] https://bugzilla.kernel.org/show_bug.cgi?id=205447

Fixes: 3726112ec731 ("block, bfq: re-schedule empty queues if they deserve I/O plugging")
Reported-by: Chris Evich 
Reported-by: Patrick Dung 
Reported-by: Thorsten Schubert 
Tested-by: Thorsten Schubert 
Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe 
Cc: Laura Abbott 
Signed-off-by: Greg Kroah-Hartman

blkcg: make blkcg_print_stat() print stats only for online blkgs

2019-11-12T18:27:04+00:00

commit b0814361a25cba73a224548843ed92d8ea78715a upstream.

blkcg_print_stat() iterates blkgs under RCU and doesn't test whether
the blkg is online.  This can call into pd_stat_fn() on a pd which is
still being initialized leading to an oops.

The heaviest operation - recursively summing up rwstat counters - is
already done while holding the queue_lock.  Expand queue_lock to cover
the other operations and skip the blkg if it isn't online yet.  The
online state is protected by both blkcg and queue locks, so this
guarantees that only online blkgs are processed.

Signed-off-by: Tejun Heo 
Reported-by: Roman Gushchin 
Cc: Josef Bacik 
Fixes: 903d23f0a354 ("blk-cgroup: allow controllers to output their own stats")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blk-rq-qos: fix first node deletion of rq_qos_del()

2019-10-29T08:22:47+00:00

commit 307f4065b9d7c1e887e8bdfb2487e4638559fea1 upstream.

rq_qos_del() incorrectly assigns the node being deleted to the head if
it was the first on the list in the !prev path.  Fix it by iterating
with ** instead.

Signed-off-by: Tejun Heo 
Cc: Josef Bacik 
Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blk-mq: honor IO scheduler for multiqueue devices

2019-10-29T08:21:32+00:00

[ Upstream commit a12de1d42d74ef3c80e9fb9a2da94daaef747869 ]

If a device is using multiple queues, the IO scheduler may be bypassed.
This may hurt performance for some slow MQ devices, and it also breaks
zoned devices which depend on mq-deadline for respecting the write order
in one zone.

Don't bypass io scheduler if we have one setup.

This patch can double sequential write performance basically on MQ
scsi_debug when mq-deadline is applied.

Cc: Bart Van Assche 
Cc: Hannes Reinecke 
Cc: Dave Chinner 
Reviewed-by: Javier González 
Reviewed-by: Damien Le Moal 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

blk-wbt: fix performance regression in wbt scale_up/scale_down

2019-10-17T20:47:13+00:00

commit b84477d3ebb96294f87dc3161e53fa8fe22d9bfd upstream.

scale_up wakes up waiters after scaling up. But after scaling max, it
should not wake up more waiters as waiters will not have anything to
do. This patch fixes this by making scale_up (and also scale_down)
return when threshold is reached.

This bug causes increased fdatasync latency when fdatasync and dd
conv=sync are performed in parallel on 4.19 compared to 4.14. This
bug was introduced during refactoring of blk-wbt code.

Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt")
Cc: stable@vger.kernel.org
Cc: Josef Bacik 
Signed-off-by: Harshad Shirwadkar 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blk-mq: move lockdep_assert_held() into elevator_exit

2019-10-11T16:36:47+00:00

[ Upstream commit 284b94be1925dbe035ce5218d8b5c197321262c7 ]

Commit c48dac137a62 ("block: don't hold q->sysfs_lock in elevator_init_mq")
removes q->sysfs_lock from elevator_init_mq(), but forgot to deal with
lockdep_assert_held() called in blk_mq_sched_free_requests() which is
run in failure path of elevator_init_mq().

blk_mq_sched_free_requests() is called in the following 3 functions:

	elevator_init_mq()
	elevator_exit()
	blk_cleanup_queue()

In blk_cleanup_queue(), blk_mq_sched_free_requests() is followed exactly
by 'mutex_lock(&q->sysfs_lock)'.

So moving the lockdep_assert_held() from blk_mq_sched_free_requests()
into elevator_exit() for fixing the report by syzbot.

Reported-by: syzbot+da3b7677bb913dc1b737@syzkaller.appspotmail.com
Fixed: c48dac137a62 ("block: don't hold q->sysfs_lock in elevator_init_mq")
Reviewed-by: Bart Van Assche 
Reviewed-by: Damien Le Moal 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block, bfq: push up injection only after setting service time

2019-10-07T17:01:40+00:00

[ Upstream commit 58494c980f40274c465ebfdece02d401def088bf ]

If equal to 0, the injection limit for a bfq_queue is pushed to 1
after a first sample of the total service time of the I/O requests of
the queue is computed (to allow injection to start). Yet, because of a
mistake in the branch that performs this action, the push may happen
also in some other case. This commit fixes this issue.

Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: fix null pointer dereference in blk_mq_rq_timed_out()

2019-10-05T13:12:29+00:00

commit 8d6996630c03d7ceeabe2611378fea5ca1c3f1b3 upstream.

We got a null pointer deference BUG_ON in blk_mq_rq_timed_out()
as following:

[  108.825472] BUG: kernel NULL pointer dereference, address: 0000000000000040
[  108.827059] PGD 0 P4D 0
[  108.827313] Oops: 0000 [#1] SMP PTI
[  108.827657] CPU: 6 PID: 198 Comm: kworker/6:1H Not tainted 5.3.0-rc8+ #431
[  108.829503] Workqueue: kblockd blk_mq_timeout_work
[  108.829913] RIP: 0010:blk_mq_check_expired+0x258/0x330
[  108.838191] Call Trace:
[  108.838406]  bt_iter+0x74/0x80
[  108.838665]  blk_mq_queue_tag_busy_iter+0x204/0x450
[  108.839074]  ? __switch_to_asm+0x34/0x70
[  108.839405]  ? blk_mq_stop_hw_queue+0x40/0x40
[  108.839823]  ? blk_mq_stop_hw_queue+0x40/0x40
[  108.840273]  ? syscall_return_via_sysret+0xf/0x7f
[  108.840732]  blk_mq_timeout_work+0x74/0x200
[  108.841151]  process_one_work+0x297/0x680
[  108.841550]  worker_thread+0x29c/0x6f0
[  108.841926]  ? rescuer_thread+0x580/0x580
[  108.842344]  kthread+0x16a/0x1a0
[  108.842666]  ? kthread_flush_work+0x170/0x170
[  108.843100]  ret_from_fork+0x35/0x40

The bug is caused by the race between timeout handle and completion for
flush request.

When timeout handle function blk_mq_rq_timed_out() try to read
'req->q->mq_ops', the 'req' have completed and reinitiated by next
flush request, which would call blk_rq_init() to clear 'req' as 0.

After commit 12f5b93145 ("blk-mq: Remove generation seqeunce"),
normal requests lifetime are protected by refcount. Until 'rq->ref'
drop to zero, the request can really be free. Thus, these requests
cannot been reused before timeout handle finish.

However, flush request has defined .end_io and rq->end_io() is still
called even if 'rq->ref' doesn't drop to zero. After that, the 'flush_rq'
can be reused by the next flush request handle, resulting in null
pointer deference BUG ON.

We fix this problem by covering flush request with 'rq->ref'.
If the refcount is not zero, flush_end_io() return and wait the
last holder recall it. To record the request status, we add a new
entry 'rq_status', which will be used in flush_end_io().

Cc: Christoph Hellwig 
Cc: Keith Busch 
Cc: Bart Van Assche 
Cc: stable@vger.kernel.org # v4.18+
Reviewed-by: Ming Lei 
Reviewed-by: Bob Liu 
Signed-off-by: Yufen Yu 
Signed-off-by: Greg Kroah-Hartman 

-------
v2:
 - move rq_status from struct request to struct blk_flush_queue
v3:
 - remove unnecessary '{}' pair.
v4:
 - let spinlock to protect 'fq->rq_status'
v5:
 - move rq_status after flush_running_idx member of struct blk_flush_queue
Signed-off-by: Jens Axboe

block: mq-deadline: Fix queue restart handling

2019-10-05T13:12:29+00:00

commit cb8acabbe33b110157955a7425ee876fb81e6bbc upstream.

Commit 7211aef86f79 ("block: mq-deadline: Fix write completion
handling") added a call to blk_mq_sched_mark_restart_hctx() in
dd_dispatch_request() to make sure that write request dispatching does
not stall when all target zones are locked. This fix left a subtle race
when a write completion happens during a dispatch execution on another
CPU:

CPU 0: Dispatch			CPU1: write completion

dd_dispatch_request()
    lock(&dd->lock);
    ...
    lock(&dd->zone_lock);	dd_finish_request()
    rq = find request		lock(&dd->zone_lock);
    unlock(&dd->zone_lock);
    				zone write unlock
				unlock(&dd->zone_lock);
				...
				__blk_mq_free_request
                                      check restart flag (not set)
				      -> queue not run
    ...
    if (!rq && have writes)
        blk_mq_sched_mark_restart_hctx()
    unlock(&dd->lock)

Since the dispatch context finishes after the write request completion
handling, marking the queue as needing a restart is not seen from
__blk_mq_free_request() and blk_mq_sched_restart() not executed leading
to the dispatch stall under 100% write workloads.

Fix this by moving the call to blk_mq_sched_mark_restart_hctx() from
dd_dispatch_request() into dd_finish_request() under the zone lock to
ensure full mutual exclusion between write request dispatch selection
and zone unlock on write request completion.

Fixes: 7211aef86f79 ("block: mq-deadline: Fix write completion handling")
Cc: stable@vger.kernel.org
Reported-by: Hans Holmberg 
Reviewed-by: Hans Holmberg 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Damien Le Moal 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman