linux-stable.git/drivers/block, branch v6.1.55

null_blk: fix poll request timeout handling

2023-09-19T10:27:56+00:00

commit 5a26e45edb4690d58406178b5a9ea4c6dcf2c105 upstream.

When doing io_uring benchmark on /dev/nullb0, it's easy to crash the
kernel if poll requests timeout triggered, as reported by David. [1]

BUG: kernel NULL pointer dereference, address: 0000000000000008
Workqueue: kblockd blk_mq_timeout_work
RIP: 0010:null_timeout_rq+0x4e/0x91
Call Trace:
 ? null_timeout_rq+0x4e/0x91
 blk_mq_handle_expired+0x31/0x4b
 bt_iter+0x68/0x84
 ? bt_tags_iter+0x81/0x81
 __sbitmap_for_each_set.constprop.0+0xb0/0xf2
 ? __blk_mq_complete_request_remote+0xf/0xf
 bt_for_each+0x46/0x64
 ? __blk_mq_complete_request_remote+0xf/0xf
 ? percpu_ref_get_many+0xc/0x2a
 blk_mq_queue_tag_busy_iter+0x14d/0x18e
 blk_mq_timeout_work+0x95/0x127
 process_one_work+0x185/0x263
 worker_thread+0x1b5/0x227

This is indeed a race problem between null_timeout_rq() and null_poll().

null_poll()				null_timeout_rq()
  spin_lock(&nq->poll_lock)
  list_splice_init(&nq->poll_list, &list)
  spin_unlock(&nq->poll_lock)

  while (!list_empty(&list))
    req = list_first_entry()
    list_del_init()
    ...
    blk_mq_add_to_batch()
    // req->rq_next = NULL
					spin_lock(&nq->poll_lock)

					// rq->queuelist->next == NULL
					list_del_init(&rq->queuelist)

					spin_unlock(&nq->poll_lock)

Fix these problems by setting requests state to MQ_RQ_COMPLETE under
nq->poll_lock protection, in which null_timeout_rq() can safely detect
this race and early return.

Note this patch just fix the kernel panic when request timeout happen.

[1] https://lore.kernel.org/all/3893581.1691785261@warthog.procyon.org.uk/

Fixes: 0a593fbbc245 ("null_blk: poll queue support")
Reported-by: David Howells 
Tested-by: David Howells 
Reviewed-by: Ming Lei 
Signed-off-by: Chengming Zhou 
Link: https://lore.kernel.org/r/20230901120306.170520-2-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

ublk: remove check IO_URING_F_SQE128 in ublk_ch_uring_cmd

2023-08-30T14:11:11+00:00

commit 9c7c4bc986932218fd0df9d2a100509772028fb1 upstream.

sizeof(struct ublksrv_io_cmd) is 16bytes, which can be held in 64byte SQE,
so not necessary to check IO_URING_F_SQE128.

With this change, we get chance to save half SQ ring memory.

Fixed: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20230220041413.1524335-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

rbd: prevent busy loop when requesting exclusive lock

2023-08-11T10:08:21+00:00

commit 9d01e07fd1bfb4daae156ab528aa196f5ac2b2bc upstream.

Due to rbd_try_acquire_lock() effectively swallowing all but
EBLOCKLISTED error from rbd_try_lock() ("request lock anyway") and
rbd_request_lock() returning ETIMEDOUT error not only for an actual
notify timeout but also when the lock owner doesn't respond, a busy
loop inside of rbd_acquire_lock() between rbd_try_acquire_lock() and
rbd_request_lock() is possible.

Requesting the lock on EBUSY error (returned by get_lock_owner_info()
if an incompatible lock or invalid lock owner is detected) makes very
little sense.  The same goes for ETIMEDOUT error (might pop up pretty
much anywhere if osd_request_timeout option is set) and many others.

Just fail I/O requests on rbd_dev->acquiring_list immediately on any
error from rbd_try_lock().

Cc: stable@vger.kernel.org # 588159009d5b: rbd: retrieve and check lock owner twice before blocklisting
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov 
Reviewed-by: Dongsheng Yang 
Signed-off-by: Greg Kroah-Hartman

rbd: retrieve and check lock owner twice before blocklisting

2023-08-03T08:24:17+00:00

commit 588159009d5b7a09c3e5904cffddbe4a4e170301 upstream.

An attempt to acquire exclusive lock can race with the current lock
owner closing the image:

1. lock is held by client123, rbd_lock() returns -EBUSY
2. get_lock_owner_info() returns client123 instance details
3. client123 closes the image, lock is released
4. find_watcher() returns 0 as there is no matching watcher anymore
5. client123 instance gets erroneously blocklisted

Particularly impacted is mirror snapshot scheduler in snapshot-based
mirroring since it happens to open and close images a lot (images are
opened only for as long as it takes to take the next mirror snapshot,
the same client instance is used for all images).

To reduce the potential for erroneous blocklisting, retrieve the lock
owner again after find_watcher() returns 0.  If it's still there, make
sure it matches the previously detected lock owner.

Cc: stable@vger.kernel.org # f38cb9d9c204: rbd: make get_lock_owner_info() return a single locker or NULL
Cc: stable@vger.kernel.org # 8ff2c64c9765: rbd: harden get_lock_owner_info() a bit
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov 
Reviewed-by: Dongsheng Yang 
Signed-off-by: Greg Kroah-Hartman

rbd: harden get_lock_owner_info() a bit

2023-08-03T08:24:17+00:00

commit 8ff2c64c9765446c3cef804fb99da04916603e27 upstream.

- we want the exclusive lock type, so test for it directly
- use sscanf() to actually parse the lock cookie and avoid admitting
  invalid handles
- bail if locker has a blank address

Signed-off-by: Ilya Dryomov 
Reviewed-by: Dongsheng Yang 
Signed-off-by: Greg Kroah-Hartman

rbd: make get_lock_owner_info() return a single locker or NULL

2023-08-03T08:24:17+00:00

commit f38cb9d9c2045dad16eead4a2e1aedfddd94603b upstream.

Make the "num_lockers can be only 0 or 1" assumption explicit and
simplify the API by getting rid of output parameters in preparation
for calling get_lock_owner_info() twice before blocklisting.

Signed-off-by: Ilya Dryomov 
Reviewed-by: Dongsheng Yang 
Signed-off-by: Greg Kroah-Hartman

ublk: fail to recover device if queue setup is interrupted

2023-08-03T08:24:07+00:00

[ Upstream commit 0c0cbd4ebc375ceebc75c89df04b74f215fab23a ]

In ublk_ctrl_end_recovery(), if wait_for_completion_interruptible() is
interrupted by signal, queues aren't setup successfully yet, so we
have to fail UBLK_CMD_END_USER_RECOVERY, otherwise kernel oops can be
triggered.

Fixes: c732a852b419 ("ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support")
Reported-by: Stefano Garzarella 
Signed-off-by: Ming Lei 
Reviewed-by: Stefano Garzarella 
Link: https://lore.kernel.org/r/20230726144502.566785-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

ublk: fail to start device if queue setup is interrupted

2023-08-03T08:24:06+00:00

[ Upstream commit 53e7d08f6d6e214c40db1f51291bb2975c789dc2 ]

In ublk_ctrl_start_dev(), if wait_for_completion_interruptible() is
interrupted by signal, queues aren't setup successfully yet, so we
have to fail UBLK_CMD_START_DEV, otherwise kernel oops can be triggered.

Reported by German when working on qemu-storage-deamon which requires
single thread ublk daemon.

Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Reported-by: German Maglione 
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20230726144502.566785-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

ublk_drv: move ublk_get_device_from_id into ublk_ctrl_uring_cmd

2023-08-03T08:24:06+00:00

[ Upstream commit bfbcef036396a73fbf4b3fee385cc670159df5ad ]

It is annoying for each control command handler to get/put ublk
device and deal with failure.

Control command handler is simplified a lot by moving
ublk_get_device_from_id into ublk_ctrl_uring_cmd().

Reviewed-by: ZiyangZhang 
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20230106041711.914434-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe 
Stable-dep-of: 53e7d08f6d6e ("ublk: fail to start device if queue setup is interrupted")
Signed-off-by: Sasha Levin

null_blk: Fix: memory release when memory_backed=1

2023-06-28T09:12:39+00:00

[ Upstream commit 8cfb98196cceec35416041c6b91212d2b99392e4 ]

Memory/pages are not freed, when unloading nullblk driver.

Steps to reproduce issue
  1.free -h
        total        used        free      shared  buff/cache   available
Mem:    7.8Gi       260Mi       7.1Gi       3.0Mi       395Mi       7.3Gi
Swap:      0B          0B          0B
  2.modprobe null_blk memory_backed=1
  3.dd if=/dev/urandom of=/dev/nullb0 oflag=direct bs=1M count=1000
  4.modprobe -r null_blk
  5.free -h
        total        used        free      shared  buff/cache   available
Mem:    7.8Gi       1.2Gi       6.1Gi       3.0Mi       398Mi       6.3Gi
Swap:      0B          0B          0B

Signed-off-by: Anuj Gupta 
Signed-off-by: Nitesh Shetty 
Link: https://lore.kernel.org/r/20230605062354.24785-1-nj.shetty@samsung.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin