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  1. 27 12月, 2019 1 次提交
    • T
      blk-mq: add optional request->alloc_time_ns · 378f7c75
      由 Tejun Heo 提交于 
      commit 6f816b4b746c2241540e537682d30d8e9997d674 upstream.

There are currently two start time timestamps - start_time_ns and
io_start_time_ns.  The former marks the request allocation and and the
second issue-to-device time.  The planned io.weight controller needs
to measure the total time bios take to execute after it leaves rq_qos
including the time spent waiting for request to become available,
which can easily dominate on saturated devices.

This patch adds request->alloc_time_ns which records when the request
allocation attempt started.  As it isn't used for the usual stats,
make it optional behind CONFIG_BLK_RQ_ALLOC_TIME and
QUEUE_FLAG_RQ_ALLOC_TIME so that it can be compiled out when there are
no users and it's active only on queues which need it even when
compiled in.

v2: s/pre_start_time/alloc_time/ and add CONFIG_BLK_RQ_ALLOC_TIME
    gating as suggested by Jens.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      378f7c75
  3. 05 10月, 2019 1 次提交
    • Y
      block: fix null pointer dereference in blk_mq_rq_timed_out() · 82652c06
      由 Yufen Yu 提交于 
      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 12f5b931 ("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 <hch@infradead.org>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: stable@vger.kernel.org # v4.18+
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Reviewed-by: NBob Liu <bob.liu@oracle.com>
Signed-off-by: NYufen Yu <yuyufen@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

-------
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: NJens Axboe <axboe@kernel.dk>
      82652c06
  5. 01 10月, 2019 2 次提交
  7. 16 9月, 2019 1 次提交
    • M
      blk-mq: free hw queue's resource in hctx's release handler · e238e6dc
      由 Ming Lei 提交于 
      [ Upstream commit c7e2d94b3d1634988a95ac4d77a72dc7487ece06 ]

Once blk_cleanup_queue() returns, tags shouldn't be used any more,
because blk_mq_free_tag_set() may be called. Commit 45a9c9d9
("blk-mq: Fix a use-after-free") fixes this issue exactly.

However, that commit introduces another issue. Before 45a9c9d9,
we are allowed to run queue during cleaning up queue if the queue's
kobj refcount is held. After that commit, queue can't be run during
queue cleaning up, otherwise oops can be triggered easily because
some fields of hctx are freed by blk_mq_free_queue() in blk_cleanup_queue().

We have invented ways for addressing this kind of issue before, such as:

	8dc765d438f1 ("SCSI: fix queue cleanup race before queue initialization is done")
	c2856ae2 ("blk-mq: quiesce queue before freeing queue")

But still can't cover all cases, recently James reports another such
kind of issue:

	https://marc.info/?l=linux-scsi&m=155389088124782&w=2

This issue can be quite hard to address by previous way, given
scsi_run_queue() may run requeues for other LUNs.

Fixes the above issue by freeing hctx's resources in its release handler, and this
way is safe becasue tags isn't needed for freeing such hctx resource.

This approach follows typical design pattern wrt. kobject's release handler.

Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: James Smart <james.smart@broadcom.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: linux-scsi@vger.kernel.org,
Cc: Martin K . Petersen <martin.petersen@oracle.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>,
Reported-by: NJames Smart <james.smart@broadcom.com>
Fixes: 45a9c9d9 ("blk-mq: Fix a use-after-free")
Cc: stable@vger.kernel.org
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Tested-by: NJames Smart <james.smart@broadcom.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      e238e6dc
  9. 15 6月, 2019 1 次提交
  11. 17 5月, 2019 1 次提交
  13. 08 5月, 2019 1 次提交
  15. 24 3月, 2019 1 次提交
    • J
      blk-mq: insert rq with DONTPREP to hctx dispatch list when requeue · 29452f66
      由 Jianchao Wang 提交于 
      [ Upstream commit aef1897cd36dcf5e296f1d2bae7e0d268561b685 ]

When requeue, if RQF_DONTPREP, rq has contained some driver
specific data, so insert it to hctx dispatch list to avoid any
merge. Take scsi as example, here is the trace event log (no
io scheduler, because RQF_STARTED would prevent merging),

   kworker/0:1H-339   [000] ...1  2037.209289: block_rq_insert: 8,0 R 4096 () 32768 + 8 [kworker/0:1H]
scsi_inert_test-1987  [000] ....  2037.220465: block_bio_queue: 8,0 R 32776 + 8 [scsi_inert_test]
scsi_inert_test-1987  [000] ...2  2037.220466: block_bio_backmerge: 8,0 R 32776 + 8 [scsi_inert_test]
   kworker/0:1H-339   [000] ....  2047.220913: block_rq_issue: 8,0 R 8192 () 32768 + 16 [kworker/0:1H]
scsi_inert_test-1996  [000] ..s1  2047.221007: block_rq_complete: 8,0 R () 32768 + 8 [0]
scsi_inert_test-1996  [000] .Ns1  2047.221045: block_rq_requeue: 8,0 R () 32776 + 8 [0]
   kworker/0:1H-339   [000] ...1  2047.221054: block_rq_insert: 8,0 R 4096 () 32776 + 8 [kworker/0:1H]
   kworker/0:1H-339   [000] ...1  2047.221056: block_rq_issue: 8,0 R 4096 () 32776 + 8 [kworker/0:1H]
scsi_inert_test-1986  [000] ..s1  2047.221119: block_rq_complete: 8,0 R () 32776 + 8 [0]

(32768 + 8) was requeued by scsi_queue_insert and had RQF_DONTPREP.
Then it was merged with (32776 + 8) and issued. Due to RQF_DONTPREP,
the sdb only contained the part of (32768 + 8), then only that part
was completed. The lucky thing was that scsi_io_completion detected
it and requeued the remaining part. So we didn't get corrupted data.
However, the requeue of (32776 + 8) is not expected.
Suggested-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      29452f66
  17. 08 12月, 2018 2 次提交
    • J
      blk-mq: punt failed direct issue to dispatch list · 55cbeea7
      由 Jens Axboe 提交于 
      commit c616cbee97aed4bc6178f148a7240206dcdb85a6 upstream.

After the direct dispatch corruption fix, we permanently disallow direct
dispatch of non read/write requests. This works fine off the normal IO
path, as they will be retried like any other failed direct dispatch
request. But for the blk_insert_cloned_request() that only DM uses to
bypass the bottom level scheduler, we always first attempt direct
dispatch. For some types of requests, that's now a permanent failure,
and no amount of retrying will make that succeed. This results in a
livelock.

Instead of making special cases for what we can direct issue, and now
having to deal with DM solving the livelock while still retaining a BUSY
condition feedback loop, always just add a request that has been through
->queue_rq() to the hardware queue dispatch list. These are safe to use
as no merging can take place there. Additionally, if requests do have
prepped data from drivers, we aren't dependent on them not sharing space
in the request structure to safely add them to the IO scheduler lists.

This basically reverts ffe81d45322c and is based on a patch from Ming,
but with the list insert case covered as well.

Fixes: ffe81d45322c ("blk-mq: fix corruption with direct issue")
Cc: stable@vger.kernel.org
Suggested-by: NMing Lei <ming.lei@redhat.com>
Reported-by: NBart Van Assche <bvanassche@acm.org>
Tested-by: NMing Lei <ming.lei@redhat.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      55cbeea7
    • J
      blk-mq: fix corruption with direct issue · 724ff9cb
      由 Jens Axboe 提交于 
      commit ffe81d45322cc3cb140f0db080a4727ea284661e upstream.

If we attempt a direct issue to a SCSI device, and it returns BUSY, then
we queue the request up normally. However, the SCSI layer may have
already setup SG tables etc for this particular command. If we later
merge with this request, then the old tables are no longer valid. Once
we issue the IO, we only read/write the original part of the request,
not the new state of it.

This causes data corruption, and is most often noticed with the file
system complaining about the just read data being invalid:

[  235.934465] EXT4-fs error (device sda1): ext4_iget:4831: inode #7142: comm dpkg-query: bad extra_isize 24937 (inode size 256)

because most of it is garbage...

This doesn't happen from the normal issue path, as we will simply defer
the request to the hardware queue dispatch list if we fail. Once it's on
the dispatch list, we never merge with it.

Fix this from the direct issue path by flagging the request as
REQ_NOMERGE so we don't change the size of it before issue.

See also:
  https://bugzilla.kernel.org/show_bug.cgi?id=201685Tested-by: NGuenter Roeck <linux@roeck-us.net>
Fixes: 6ce3dd6e ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      724ff9cb
  19. 28 9月, 2018 1 次提交
  21. 21 8月, 2018 2 次提交
    • J
      blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter · f5bbbbe4
      由 Jianchao Wang 提交于 
      For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to
account the inflight requests. It will access the queue_hw_ctx and
nr_hw_queues w/o any protection. When updating nr_hw_queues and
blk_mq_in_flight/rw occur concurrently, panic comes up.

Before update nr_hw_queues, the q will be frozen. So we could use
q_usage_counter to avoid the race. percpu_ref_is_zero is used here
so that we will not miss any in-flight request. The access to
nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are
under rcu critical section, __blk_mq_update_nr_hw_queues could use
synchronize_rcu to ensure the zeroed q_usage_counter to be globally
visible.
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      f5bbbbe4
    • J
      blk-mq: init hctx sched after update ctx and hctx mapping · d48ece20
      由 Jianchao Wang 提交于 
      Currently, when update nr_hw_queues, IO scheduler's init_hctx will
be invoked before the mapping between ctx and hctx is adapted
correctly by blk_mq_map_swqueue. The IO scheduler init_hctx (kyber)
may depend on this mapping and get wrong result and panic finally.
A simply way to fix this is that switch the IO scheduler to 'none'
before update the nr_hw_queues, and then switch it back after
update nr_hw_queues. blk_mq_sched_init_/exit_hctx are removed due
to nobody use them any more.
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      d48ece20
  23. 09 8月, 2018 1 次提交
    • J
      blk-mq: count the hctx as active before allocating tag · d263ed99
      由 Jianchao Wang 提交于 
      Currently, we count the hctx as active after allocate driver tag
successfully. If a previously inactive hctx try to get tag first
time, it may fails and need to wait. However, due to the stale tag
->active_queues, the other shared-tags users are still able to
occupy all driver tags while there is someone waiting for tag.
Consequently, even if the previously inactive hctx is waked up, it
still may not be able to get a tag and could be starved.

To fix it, we count the hctx as active before try to allocate driver
tag, then when it is waiting the tag, the other shared-tag users
will reserve budget for it.
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      d263ed99
  25. 25 7月, 2018 1 次提交
  27. 23 7月, 2018 1 次提交
    • M
      blk-mq: fail the request in case issue failure · 8824f622
      由 Ming Lei 提交于 
      Inside blk_mq_try_issue_list_directly(), if the request is issued as
failed, we shouldn't try to do it again, otherwise the warning in
blk_mq_start_request() will be triggered. This change is aligned to
behaviour of other ways of request issue & dispatch.

Fixes: 6ce3dd6e ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: kernel test robot <rong.a.chen@intel.com>
Cc: LKP <lkp@01.org>
Reported-by: Nkernel test robot <rong.a.chen@intel.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      8824f622
  29. 18 7月, 2018 1 次提交
    • M
      blk-mq: issue directly if hw queue isn't busy in case of 'none' · 6ce3dd6e
      由 Ming Lei 提交于 
      In case of 'none' io scheduler, when hw queue isn't busy, it isn't
necessary to enqueue request to sw queue and dequeue it from
sw queue because request may be submitted to hw queue asap without
extra cost, meantime there shouldn't be much request in sw queue,
and we don't need to worry about effect on IO merge.

There are still some single hw queue SCSI HBAs(HPSA, megaraid_sas, ...)
which may connect high performance devices, so 'none' is often required
for obtaining good performance.

This patch improves IOPS and decreases CPU unilization on megaraid_sas,
per Kashyap's test.

Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Reported-by: NKashyap Desai <kashyap.desai@broadcom.com>
Tested-by: NKashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      6ce3dd6e
  31. 09 7月, 2018 10 次提交
  33. 29 6月, 2018 1 次提交
    • J
      blk-mq: don't queue more if we get a busy return · 1f57f8d4
      由 Jens Axboe 提交于 
      Some devices have different queue limits depending on the type of IO. A
classic case is SATA NCQ, where some commands can queue, but others
cannot. If we have NCQ commands inflight and encounter a non-queueable
command, the driver returns busy. Currently we attempt to dispatch more
from the scheduler, if we were able to queue some commands. But for the
case where we ended up stopping due to BUSY, we should not attempt to
retrieve more from the scheduler. If we do, we can get into a situation
where we attempt to queue a non-queueable command, get BUSY, then
successfully retrieve more commands from that scheduler and queue those.
This can repeat forever, starving the non-queuable command indefinitely.

Fix this by NOT attempting to pull more commands from the scheduler, if
we get a BUSY return. This should also be more optimal in terms of
letting requests stay in the scheduler for as long as possible, if we
get a BUSY due to the regular out-of-tags condition.
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      1f57f8d4
  35. 24 6月, 2018 1 次提交
  37. 14 6月, 2018 1 次提交
  39. 13 6月, 2018 1 次提交
    • K
      treewide: kzalloc_node() -> kcalloc_node() · 590b5b7d
      由 Kees Cook 提交于 
      The kzalloc_node() function has a 2-factor argument form, kcalloc_node(). This
patch replaces cases of:

        kzalloc_node(a * b, gfp, node)

with:
        kcalloc_node(a * b, gfp, node)

as well as handling cases of:

        kzalloc_node(a * b * c, gfp, node)

with:

        kzalloc_node(array3_size(a, b, c), gfp, node)

as it's slightly less ugly than:

        kcalloc_node(array_size(a, b), c, gfp, node)

This does, however, attempt to ignore constant size factors like:

        kzalloc_node(4 * 1024, gfp, node)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kzalloc_node(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kzalloc_node(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kzalloc_node(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kzalloc_node(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kzalloc_node
+ kcalloc_node
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kzalloc_node(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc_node(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc_node(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc_node(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kzalloc_node(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kzalloc_node(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc_node(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kzalloc_node(C1 * C2 * C3, ...)
|
  kzalloc_node(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc_node(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc_node(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc_node(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kzalloc_node(sizeof(THING) * C2, ...)
|
  kzalloc_node(sizeof(TYPE) * C2, ...)
|
  kzalloc_node(C1 * C2 * C3, ...)
|
  kzalloc_node(C1 * C2, ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kzalloc_node
+ kcalloc_node
  (
-	E1 * E2
+	E1, E2
  , ...)
)
Signed-off-by: NKees Cook <keescook@chromium.org>
      590b5b7d
  41. 11 6月, 2018 1 次提交
    • R
      blk-mq: reinit q->tag_set_list entry only after grace period · a347c7ad
      由 Roman Pen 提交于 
      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]  <IRQ>
[ 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]  </IRQ>

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: 705cda97 ("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 <sagi@grimberg.me>
Cc: linux-block@vger.kernel.org
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NRoman Pen <roman.penyaev@profitbricks.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      a347c7ad
  43. 05 6月, 2018 1 次提交
  45. 01 6月, 2018 2 次提交
  47. 29 5月, 2018 4 次提交