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Jens Axboe 73027d80d6 blk-mq: fix discard merge with scheduler attached 
[ Upstream commit 445251d0f4 ]

I ran into an issue on my laptop that triggered a bug on the
discard path:

WARNING: CPU: 2 PID: 207 at drivers/nvme/host/core.c:527 nvme_setup_cmd+0x3d3/0x430
 Modules linked in: rfcomm fuse ctr ccm bnep arc4 binfmt_misc snd_hda_codec_hdmi nls_iso8859_1 nls_cp437 vfat snd_hda_codec_conexant fat snd_hda_codec_generic iwlmvm snd_hda_intel snd_hda_codec snd_hwdep mac80211 snd_hda_core snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq x86_pkg_temp_thermal intel_powerclamp kvm_intel uvcvideo iwlwifi btusb snd_seq_device videobuf2_vmalloc btintel videobuf2_memops kvm snd_timer videobuf2_v4l2 bluetooth irqbypass videobuf2_core aesni_intel aes_x86_64 crypto_simd cryptd snd glue_helper videodev cfg80211 ecdh_generic soundcore hid_generic usbhid hid i915 psmouse e1000e ptp pps_core xhci_pci xhci_hcd intel_gtt
 CPU: 2 PID: 207 Comm: jbd2/nvme0n1p7- Tainted: G     U           4.15.0+ #176
 Hardware name: LENOVO 20FBCTO1WW/20FBCTO1WW, BIOS N1FET59W (1.33 ) 12/19/2017
 RIP: 0010:nvme_setup_cmd+0x3d3/0x430
 RSP: 0018:ffff880423e9f838 EFLAGS: 00010217
 RAX: 0000000000000000 RBX: ffff880423e9f8c8 RCX: 0000000000010000
 RDX: ffff88022b200010 RSI: 0000000000000002 RDI: 00000000327f0000
 RBP: ffff880421251400 R08: ffff88022b200000 R09: 0000000000000009
 R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000ffff
 R13: ffff88042341e280 R14: 000000000000ffff R15: ffff880421251440
 FS:  0000000000000000(0000) GS:ffff880441500000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055b684795030 CR3: 0000000002e09006 CR4: 00000000001606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  nvme_queue_rq+0x40/0xa00
  ? __sbitmap_queue_get+0x24/0x90
  ? blk_mq_get_tag+0xa3/0x250
  ? wait_woken+0x80/0x80
  ? blk_mq_get_driver_tag+0x97/0xf0
  blk_mq_dispatch_rq_list+0x7b/0x4a0
  ? deadline_remove_request+0x49/0xb0
  blk_mq_do_dispatch_sched+0x4f/0xc0
  blk_mq_sched_dispatch_requests+0x106/0x170
  __blk_mq_run_hw_queue+0x53/0xa0
  __blk_mq_delay_run_hw_queue+0x83/0xa0
  blk_mq_run_hw_queue+0x6c/0xd0
  blk_mq_sched_insert_request+0x96/0x140
  __blk_mq_try_issue_directly+0x3d/0x190
  blk_mq_try_issue_directly+0x30/0x70
  blk_mq_make_request+0x1a4/0x6a0
  generic_make_request+0xfd/0x2f0
  ? submit_bio+0x5c/0x110
  submit_bio+0x5c/0x110
  ? __blkdev_issue_discard+0x152/0x200
  submit_bio_wait+0x43/0x60
  ext4_process_freed_data+0x1cd/0x440
  ? account_page_dirtied+0xe2/0x1a0
  ext4_journal_commit_callback+0x4a/0xc0
  jbd2_journal_commit_transaction+0x17e2/0x19e0
  ? kjournald2+0xb0/0x250
  kjournald2+0xb0/0x250
  ? wait_woken+0x80/0x80
  ? commit_timeout+0x10/0x10
  kthread+0x111/0x130
  ? kthread_create_worker_on_cpu+0x50/0x50
  ? do_group_exit+0x3a/0xa0
  ret_from_fork+0x1f/0x30
 Code: 73 89 c1 83 ce 10 c1 e1 10 09 ca 83 f8 04 0f 87 0f ff ff ff 8b 4d 20 48 8b 7d 00 c1 e9 09 48 01 8c c7 00 08 00 00 e9 f8 fe ff ff <0f> ff 4c 89 c7 41 bc 0a 00 00 00 e8 0d 78 d6 ff e9 a1 fc ff ff
 ---[ end trace 50d361cc444506c8 ]---
 print_req_error: I/O error, dev nvme0n1, sector 847167488

Decoding the assembly, the request claims to have 0xffff segments,
while nvme counts two. This turns out to be because we don't check
for a data carrying request on the mq scheduler path, and since
blk_phys_contig_segment() returns true for a non-data request,
we decrement the initial segment count of 0 and end up with
0xffff in the unsigned short.

There are a few issues here:

1) We should initialize the segment count for a discard to 1.
2) The discard merging is currently using the data limits for
   segments and sectors.

Fix this up by having attempt_merge() correctly identify the
request, and by initializing the segment count correctly
for discards.

This can only be triggered with mq-deadline on discard capable
devices right now, which isn't a common configuration.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2018-04-26 11:02:15 +02:00
..
partitions partitions/msdos: Unable to mount UFS 44bsd partitions 2018-04-08 14:26:28 +02:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig.iosched License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
badblocks.c badblocks: fix wrong return value in badblocks_set if badblocks are disabled 2017-12-20 10:10:26 +01:00
bfq-cgroup.c block, bfq: put async queues for root bfq groups too 2018-04-12 12:32:19 +02:00
bfq-iosched.c block,bfq: Disable writeback throttling 2017-12-25 14:26:26 +01:00
bfq-iosched.h Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
bfq-wf2q.c block, bfq: guarantee update_next_in_service always returns an eligible entity 2017-08-31 08:20:31 -06:00
bio-integrity.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
bio.c block: Set BIO_TRACE_COMPLETION on new bio during split 2018-04-26 11:02:10 +02:00
blk-cgroup.c blkcg: avoid free blkcg_root when failed to alloc blkcg policy 2017-08-25 13:51:07 -06:00
blk-core.c blk-mq: fix discard merge with scheduler attached 2018-04-26 11:02:15 +02:00
blk-exec.c block: introduce new block status code type 2017-06-09 09:27:32 -06:00
blk-flush.c block: update comments to reflect REQ_FLUSH -> REQ_PREFLUSH rename 2017-08-25 10:36:54 -06:00
blk-integrity.c block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
blk-ioc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-lib.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-map.c blk_rq_map_user_iov: fix error override 2018-02-25 11:07:49 +01:00
blk-merge.c blk-mq: fix discard merge with scheduler attached 2018-04-26 11:02:15 +02:00
blk-mq-cpumap.c blk-mq: don't keep offline CPUs mapped to hctx 0 2018-04-19 08:56:20 +02:00
blk-mq-debugfs.c blk-mq-debugfs: don't allow write on attributes with seq_operations set 2018-04-26 11:02:11 +02:00
blk-mq-debugfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-mq-pci.c blk-mq-pci: add a fallback when pci_irq_get_affinity returns NULL 2017-08-18 08:08:14 -06:00
blk-mq-rdma.c block: Add rdma affinity based queue mapping helper 2017-08-08 14:58:03 -04:00
blk-mq-sched.c blk-mq-sched: dispatch from scheduler IFF progress is made in ->dispatch 2017-12-20 10:10:27 +01:00
blk-mq-sched.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-mq-sysfs.c blk-mq: untangle debugfs and sysfs 2017-05-04 08:24:13 -06:00
blk-mq-tag.c blk-mq: Make blk_mq_reinit_tagset() calls easier to read 2017-08-18 08:36:58 -06:00
blk-mq-tag.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-mq-virtio.c blk-mq: provide a default queue mapping for virtio device 2017-02-27 20:54:05 +02:00
blk-mq.c blk-mq: turn WARN_ON in __blk_mq_run_hw_queue into printk 2018-04-26 11:02:07 +02:00
blk-mq.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-settings.c block: Warn if blk_queue_rq_timed_out() is called for a blk-mq queue 2017-08-23 12:02:30 -06:00
blk-softirq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-stat.c blk-stat: don't use this_cpu_ptr() in a preemptable section 2017-05-10 07:40:18 -06:00
blk-stat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-sysfs.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-tag.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-throttle.c block-throttle: avoid double charge 2017-12-29 17:53:47 +01:00
blk-timeout.c block: Fix a race between blk_cleanup_queue() and timeout handling 2017-11-30 08:40:52 +00:00
blk-wbt.c blk-wbt: account flush requests correctly 2018-02-22 15:42:29 +01:00
blk-wbt.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-zoned.c block: replace bi_bdev with a gendisk pointer and partitions index 2017-08-23 12:49:55 -06:00
blk.h block: drain queue before waiting for q_usage_counter becoming zero 2018-03-03 10:24:35 +01:00
bounce.c block: don't let passthrough IO go into .make_request_fn() 2018-01-02 20:31:05 +01:00
bsg-lib.c bsg-lib: fix use-after-free under memory-pressure 2017-10-04 08:35:04 -06:00
bsg.c bsg: remove #if 0'ed code 2017-08-29 10:50:30 -06:00
cfq-iosched.c block/cfq: cache rightmost rb_node 2017-09-08 18:26:49 -07:00
cmdline-parser.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat_ioctl.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
deadline-iosched.c block, scheduler: convert xxx_var_store to void 2017-08-28 10:01:08 -06:00
elevator.c block: fix warning when I/O elevator is changed as request_queue is being removed 2017-08-28 10:52:44 -06:00
genhd.c Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
ioctl.c block: remove the discard_zeroes_data flag 2017-04-08 11:25:38 -06:00
ioprio.c block: Add fallthrough markers to switch statements 2017-06-21 11:46:07 -06:00
kyber-iosched.c block: kyber: fix domain token leak during requeue 2018-03-08 22:41:05 -08:00
mq-deadline.c mq-deadline: Enable auto-loading when built as module 2017-08-29 10:47:23 -06:00
noop-iosched.c block: move existing elevator ops to union 2017-01-17 10:03:33 -07:00
opal_proto.h block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
partition-generic.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
scsi_ioctl.c block: Change argument type of scsi_req_init() 2017-06-20 19:27:14 -06:00
sed-opal.c block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
t10-pi.c t10-pi: Move opencoded contants to common header 2017-07-03 16:56:25 -06:00