[PATCH] block: re-introduce blk_mq_complete_request_sync
Sagi Grimberg
sagi at grimberg.me
Fri Oct 9 04:09:16 EDT 2020
> Hi Sagi
>
> I applied this patch on block origin/for-next and still can reproduce it.
That's unexpected, can you try this patch?
--
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 629b025685d1..46428ff0b0fc 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2175,7 +2175,7 @@ static void nvme_tcp_complete_timed_out(struct
request *rq)
/* fence other contexts that may complete the command */
mutex_lock(&to_tcp_ctrl(ctrl)->teardown_lock);
nvme_tcp_stop_queue(ctrl, nvme_tcp_queue_id(req->queue));
- if (!blk_mq_request_completed(rq)) {
+ if (blk_mq_request_started(rq) && !blk_mq_request_completed(rq)) {
nvme_req(rq)->status = NVME_SC_HOST_ABORTED_CMD;
blk_mq_complete_request_sync(rq);
}
--
>
> [ 724.267865] run blktests nvme/012 at 2020-10-09 00:48:52
> [ 724.518498] loop: module loaded
> [ 724.552880] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
> [ 724.586609] nvmet_tcp: enabling port 0 (127.0.0.1:4420)
> [ 724.648898] nvmet: creating controller 1 for subsystem blktests-subsystem-1 for NQN nqn.2014-08.org.nvmexpress:uuid:e544149126a24145abeeb6129b0ec52c.
> [ 724.663300] nvme nvme0: creating 12 I/O queues.
> [ 724.669826] nvme nvme0: mapped 12/0/0 default/read/poll queues.
> [ 724.681350] nvme nvme0: new ctrl: NQN "blktests-subsystem-1", addr 127.0.0.1:4420
> [ 726.641605] XFS (nvme0n1): Mounting V5 Filesystem
> [ 726.654637] XFS (nvme0n1): Ending clean mount
> [ 726.660302] xfs filesystem being mounted at /mnt/blktests supports timestamps until 2038 (0x7fffffff)
> [ 787.042066] nvme nvme0: queue 2: timeout request 0xe type 4
> [ 787.047649] nvme nvme0: starting error recovery
> [ 787.052211] nvme nvme0: queue 4: timeout request 0x61 type 4
> [ 787.053407] block nvme0n1: no usable path - requeuing I/O
> [ 787.054543] nvme nvme0: Reconnecting in 10 seconds...
> [ 787.057877] ------------[ cut here ]------------
> [ 787.063274] block nvme0n1: no usable path - requeuing I/O
> [ 787.068313] refcount_t: underflow; use-after-free.
> [ 787.068370] WARNING: CPU: 3 PID: 30 at lib/refcount.c:28 refcount_warn_saturate+0xa6/0xf0
> [ 787.072941] block nvme0n1: no usable path - requeuing I/O
> [ 787.072945] block nvme0n1: no usable path - requeuing I/O
> [ 787.078333] Modules linked in: loop nvme_tcp nvme_fabrics nvme_core nvmet_tcp nvmet rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache sunrpc snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_timer amd64_edac_mod snd edac_mce_amd soundcore kvm_amd ccp kvm pcspkr irqbypass hp_wmi sparse_keymap rfkill k10temp wmi_bmof nv_tco i2c_nforce2 acpi_cpufreq ip_tables xfs nouveau video mxm_wmi i2c_algo_bit drm_kms_helper mptsas cec scsi_transport_sas ttm mptscsih ata_generic firewire_ohci pata_acpi firewire_core drm serio_raw mptbase forcedeth crc_itu_t sata_nv pata_amd wmi floppy
> [ 787.083142] block nvme0n1: no usable path - requeuing I/O
> [ 787.091304] CPU: 3 PID: 30 Comm: kworker/3:0H Not tainted 5.9.0-rc8.update+ #3
> [ 787.096673] block nvme0n1: no usable path - requeuing I/O
> [ 787.096674] block nvme0n1: no usable path - requeuing I/O
> [ 787.096680] block nvme0n1: no usable path - requeuing I/O
> [ 787.096681] block nvme0n1: no usable path - requeuing I/O
> [ 787.096683] block nvme0n1: no usable path - requeuing I/O
> [ 787.201242] Hardware name: Hewlett-Packard HP xw9400 Workstation/0A1Ch, BIOS 786D6 v04.02 04/21/2009
> [ 787.210366] Workqueue: kblockd blk_mq_timeout_work
> [ 787.215161] RIP: 0010:refcount_warn_saturate+0xa6/0xf0
> [ 787.220295] Code: 05 aa 98 22 01 01 e8 9f cf ad ff 0f 0b c3 80 3d 98 98 22 01 00 75 95 48 c7 c7 48 54 3e a2 c6 05 88 98 22 01 01 e8 80 cf ad ff <0f> 0b c3 80 3d 77 98 22 01 00 0f 85 72 ff ff ff 48 c7 c7 a0 54 3e
> [ 787.239021] RSP: 0018:ffffb860407b3dc8 EFLAGS: 00010292
> [ 787.244240] RAX: 0000000000000026 RBX: 0000000000000000 RCX: ffff9d93ddc58d08
> [ 787.251361] RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffff9d93ddc58d00
> [ 787.258480] RBP: ffff9d93dbd6c200 R08: 000000b740ed60e8 R09: ffffffffa2fffbc4
> [ 787.265612] R10: 0000000000000477 R11: 0000000000028320 R12: ffff9d93dbd6c2e8
> [ 787.272741] R13: ffff9d93dbea0000 R14: ffffb860407b3e70 R15: ffff9d93dbea0000
> [ 787.279864] FS: 0000000000000000(0000) GS:ffff9d93ddc40000(0000) knlGS:0000000000000000
> [ 787.287948] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 787.293695] CR2: 00007f45fd8fa024 CR3: 00000000792dc000 CR4: 00000000000006e0
> [ 787.300820] Call Trace:
> [ 787.303277] blk_mq_check_expired+0x109/0x1b0
> [ 787.307638] blk_mq_queue_tag_busy_iter+0x1b8/0x330
> [ 787.312524] ? blk_poll+0x300/0x300
> [ 787.316022] blk_mq_timeout_work+0x44/0xe0
> [ 787.320128] process_one_work+0x1b4/0x370
> [ 787.324137] worker_thread+0x53/0x3e0
> [ 787.327809] ? process_one_work+0x370/0x370
> [ 787.332015] kthread+0x11b/0x140
> [ 787.335245] ? __kthread_bind_mask+0x60/0x60
> [ 787.339515] ret_from_fork+0x22/0x30
> [ 787.343094] ---[ end trace 606cf9189379fcfc ]---
>
>
> Best Regards,
> Yi Zhang
>
>
> ----- Original Message -----
> From: "Ming Lei" <ming.lei at redhat.com>
> To: "Sagi Grimberg" <sagi at grimberg.me>
> Cc: "Jens Axboe" <axboe at kernel.dk>, "Yi Zhang" <yi.zhang at redhat.com>, linux-nvme at lists.infradead.org, linux-block at vger.kernel.org, "Keith Busch" <kbusch at kernel.org>, "Christoph Hellwig" <hch at lst.de>
> Sent: Friday, October 9, 2020 12:39:38 PM
> Subject: Re: [PATCH] block: re-introduce blk_mq_complete_request_sync
>
> On Thu, Oct 08, 2020 at 02:37:50PM -0700, Sagi Grimberg wrote:
>> In nvme-tcp and nvme-rdma, the timeout handler in certain conditions
>> needs to complete an aborted request. The timeout handler serializes
>> against an error recovery sequence that iterates over the inflight
>> requests and cancels them.
>>
>> However, the fact that blk_mq_complete_request may defer to a different
>> core that serialization breaks.
>>
>> Hence re-introduce blk_mq_complete_request_sync and use that in the
>> timeout handler to make sure that we don't get a use-after-free
>> condition.
>>
>> This was uncovered by the blktests:
>> --
>> $ nvme_trtype=tcp ./check nvme/012
>>
>> [ 2152.546343] run blktests nvme/012 at 2020-10-08 05:59:03
>> [ 2152.799640] loop: module loaded
>> [ 2152.835222] nvmet: adding nsid 1 to subsystem blktests-subsystem-1
>> [ 2152.860697] nvmet_tcp: enabling port 0 (127.0.0.1:4420)
>> [ 2152.937889] nvmet: creating controller 1 for subsystem blktests-subsystem-1 for NQN nqn.2014-08.org.nvmexpress:uuid:e544149126a24145abeeb6129b0ec52c.
>> [ 2152.952085] nvme nvme0: creating 12 I/O queues.
>> [ 2152.958042] nvme nvme0: mapped 12/0/0 default/read/poll queues.
>> [ 2152.969948] nvme nvme0: new ctrl: NQN "blktests-subsystem-1", addr 127.0.0.1:4420
>> [ 2154.927953] XFS (nvme0n1): Mounting V5 Filesystem
>> [ 2154.942432] XFS (nvme0n1): Ending clean mount
>> [ 2154.948183] xfs filesystem being mounted at /mnt/blktests supports timestamps until 2038 (0x7fffffff)
>> [ 2215.193645] nvme nvme0: queue 7: timeout request 0x11 type 4
>> [ 2215.199331] nvme nvme0: starting error recovery
>> [ 2215.203890] nvme nvme0: queue 7: timeout request 0x12 type 4
>> [ 2215.204483] block nvme0n1: no usable path - requeuing I/O
>> [ 2215.214976] block nvme0n1: no usable path - requeuing I/O
>> [ 2215.215495] nvme nvme0: Reconnecting in 10 seconds...
>> [ 2215.215502] ------------[ cut here ]------------
>> [ 2215.215505] refcount_t: underflow; use-after-free.
>> [ 2215.215617] WARNING: CPU: 6 PID: 45 at lib/refcount.c:28 refcount_warn_saturate+0xa6/0xf0
>> [ 2215.215745] RSP: 0018:ffffb71b80837dc8 EFLAGS: 00010292
>> [ 2215.215750] RAX: 0000000000000026 RBX: 0000000000000000 RCX: ffff93f37dcd8d08
>> [ 2215.215753] RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffff93f37dcd8d00
>> [ 2215.215755] RBP: ffff93f37a812400 R08: 00000203c5221fce R09: ffffffffa7fffbc4
>> [ 2215.215758] R10: 0000000000000477 R11: 000000000002835c R12: ffff93f37a8124e8
>> [ 2215.215761] R13: ffff93f37a2b0000 R14: ffffb71b80837e70 R15: ffff93f37a2b0000
>> [ 2215.215765] FS: 0000000000000000(0000) GS:ffff93f37dcc0000(0000) knlGS:0000000000000000
>> [ 2215.215768] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 2215.215771] CR2: 00005637b4137028 CR3: 000000007c1be000 CR4: 00000000000006e0
>> [ 2215.215773] Call Trace:
>> [ 2215.215784] blk_mq_check_expired+0x109/0x1b0
>> [ 2215.215797] blk_mq_queue_tag_busy_iter+0x1b8/0x330
>> [ 2215.215801] ? blk_poll+0x300/0x300
>> [ 2215.215806] blk_mq_timeout_work+0x44/0xe0
>> [ 2215.215814] process_one_work+0x1b4/0x370
>> [ 2215.215820] worker_thread+0x53/0x3e0
>> [ 2215.215825] ? process_one_work+0x370/0x370
>> [ 2215.215829] kthread+0x11b/0x140
>> [ 2215.215834] ? __kthread_bind_mask+0x60/0x60
>> [ 2215.215841] ret_from_fork+0x22/0x30
>> [ 2215.215847] ---[ end trace 7d137e36e23c0d19 ]---
>> --
>>
>> Reported-by: Yi Zhang <yi.zhang at redhat.com>
>> Fixes: 236187c4ed19 ("nvme-tcp: fix timeout handler")
>> Fixes: 0475a8dcbcee ("nvme-rdma: fix timeout handler")
>> Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
>> ---
>> Yi, would appreciate your Tested-by tag
>>
>> block/blk-mq.c | 7 +++++++
>> drivers/nvme/host/rdma.c | 2 +-
>> drivers/nvme/host/tcp.c | 2 +-
>> include/linux/blk-mq.h | 1 +
>> 4 files changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>> index f8e1e759c905..2d154722ef39 100644
>> --- a/block/blk-mq.c
>> +++ b/block/blk-mq.c
>> @@ -729,6 +729,13 @@ bool blk_mq_complete_request_remote(struct request *rq)
>> }
>> EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote);
>>
>> +void blk_mq_complete_request_sync(struct request *rq)
>> +{
>> + WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
>> + rq->q->mq_ops->complete(rq);
>> +}
>> +EXPORT_SYMBOL_GPL(blk_mq_complete_request_sync);
>> +
>> /**
>> * blk_mq_complete_request - end I/O on a request
>> * @rq: the request being processed
>> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
>> index 9e378d0a0c01..45fc605349da 100644
>> --- a/drivers/nvme/host/rdma.c
>> +++ b/drivers/nvme/host/rdma.c
>> @@ -1975,7 +1975,7 @@ static void nvme_rdma_complete_timed_out(struct request *rq)
>> nvme_rdma_stop_queue(queue);
>> if (!blk_mq_request_completed(rq)) {
>> nvme_req(rq)->status = NVME_SC_HOST_ABORTED_CMD;
>> - blk_mq_complete_request(rq);
>> + blk_mq_complete_request_sync(rq);
>> }
>> mutex_unlock(&ctrl->teardown_lock);
>> }
>> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
>> index 8f4f29f18b8c..629b025685d1 100644
>> --- a/drivers/nvme/host/tcp.c
>> +++ b/drivers/nvme/host/tcp.c
>> @@ -2177,7 +2177,7 @@ static void nvme_tcp_complete_timed_out(struct request *rq)
>> nvme_tcp_stop_queue(ctrl, nvme_tcp_queue_id(req->queue));
>> if (!blk_mq_request_completed(rq)) {
>> nvme_req(rq)->status = NVME_SC_HOST_ABORTED_CMD;
>> - blk_mq_complete_request(rq);
>> + blk_mq_complete_request_sync(rq);
>
> Or complete the request in the following way? Then one block layer API
> can be saved:
>
> blk_mq_complete_request_remote(rq);
> nvme_complete_rq(rq);
>
>
> thanks,
> Ming
>
>
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>
>
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