INFO: task hung in blk_mq_get_tag

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 4e76528b Merge 4.14.81 into android-4.14
git tree: android-4.14
console output: https://syzkaller.appspot.com/x/log.txt?x=12d7a225400000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e4a95e0186919ba
dashboard link: https://syzkaller.appspot.com/bug?extid=8b387a1474246a746023
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+8b387a...@syzkaller.appspotmail.com

b_state=0x0000012d, b_size=1024
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=4
b_state=0x0000012d, b_size=1024
device loop0 blocksize: 4096
INFO: task kworker/u4:13:5419 blocked for more than 140 seconds.
Not tainted 4.14.81+ #6
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:13 D26200 5419 2 0x80000000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
schedule+0x7f/0x1b0 kernel/sched/core.c:3490
io_schedule+0x1c/0x70 kernel/sched/core.c:5097
blk_mq_get_tag+0x3a1/0xa20 block/blk-mq-tag.c:161
blk_mq_get_request+0x452/0x1420 block/blk-mq.c:382
blk_mq_make_request+0x2db/0x1a60 block/blk-mq.c:1669
generic_make_request+0x214/0x870 block/blk-core.c:2229
submit_bio+0xa7/0x3a0 block/blk-core.c:2303
submit_bh_wbc.isra.17+0x45f/0x5f0 fs/buffer.c:3144
__block_write_full_page+0x4ee/0x980 fs/buffer.c:1826
block_write_full_page+0x227/0x280 fs/buffer.c:3012
__writepage+0x5f/0xc0 mm/page-writeback.c:2302
write_cache_pages+0x518/0xe90 mm/page-writeback.c:2240
generic_writepages+0xda/0x150 mm/page-writeback.c:2326
do_writepages+0xe0/0x270 mm/page-writeback.c:2341
__writeback_single_inode+0xd8/0x1020 fs/fs-writeback.c:1320
writeback_sb_inodes+0x468/0xcd0 fs/fs-writeback.c:1584
__writeback_inodes_wb+0xf8/0x1e0 fs/fs-writeback.c:1653
wb_writeback+0x4ee/0xb90 fs/fs-writeback.c:1762
wb_do_writeback fs/fs-writeback.c:1892 [inline]
wb_workfn+0x1e0/0xe00 fs/fs-writeback.c:1928
process_one_work+0x86e/0x1670 kernel/workqueue.c:2114
worker_thread+0xdc/0x1000 kernel/workqueue.c:2248
kthread+0x348/0x420 kernel/kthread.c:232
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402
INFO: task blkid:17076 blocked for more than 140 seconds.
Not tainted 4.14.81+ #6
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
blkid D26792 17076 313 0x00000004
Call Trace:
schedule+0x7f/0x1b0 kernel/sched/core.c:3490
io_schedule+0x1c/0x70 kernel/sched/core.c:5097
blk_mq_get_tag+0x3a1/0xa20 block/blk-mq-tag.c:161
blk_mq_get_request+0x452/0x1420 block/blk-mq.c:382
blk_mq_make_request+0x2db/0x1a60 block/blk-mq.c:1669
generic_make_request+0x214/0x870 block/blk-core.c:2229
submit_bio+0xa7/0x3a0 block/blk-core.c:2303
submit_bh_wbc.isra.17+0x45f/0x5f0 fs/buffer.c:3144
submit_bh fs/buffer.c:3150 [inline]
block_read_full_page+0x66b/0x7c0 fs/buffer.c:2355
generic_file_buffered_read mm/filemap.c:2130 [inline]
generic_file_read_iter+0xa9d/0x1ab0 mm/filemap.c:2263
blkdev_read_iter+0xfe/0x160 fs/block_dev.c:1926
call_read_iter include/linux/fs.h:1776 [inline]
new_sync_read fs/read_write.c:401 [inline]
__vfs_read+0x414/0x5b0 fs/read_write.c:413
vfs_read+0x11e/0x330 fs/read_write.c:447
SYSC_read fs/read_write.c:577 [inline]
SyS_read+0xc2/0x1a0 fs/read_write.c:570
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7f504766f310
RSP: 002b:00007ffeef70af18 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000080f0000 RCX: 00007f504766f310
RDX: 0000000000000040 RSI: 00000000021c5c58 RDI: 0000000000000003
RBP: 00000000021c5c30 R08: 0000000000000068 R09: 0101010101010101
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000021c5030
R13: 0000000000000040 R14: 00000000021c5080 R15: 00000000021c5c48

Showing all locks held in the system:
1 lock held by khungtaskd/23:
#0: (tasklist_lock){.+.+}, at: [<ffffffff908023b7>]
debug_show_all_locks+0x74/0x20f kernel/locking/lockdep.c:4541
1 lock held by rsyslogd/1632:
#0: (&f->f_pos_lock){+.+.}, at: [<ffffffff90bbdcf2>]
__fdget_pos+0xa2/0xc0 fs/file.c:768
2 locks held by getty/1760:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff9133cf30>]
tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff913384af>]
n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142
3 locks held by kworker/u4:13/5419:
#0: ("writeback"){+.+.}, at: [<ffffffff90727d04>]
process_one_work+0x784/0x1670 kernel/workqueue.c:2085
#1: ((&(&wb->dwork)->work)){+.+.}, at: [<ffffffff90727d3c>]
process_one_work+0x7bc/0x1670 kernel/workqueue.c:2089
#2: (&type->s_umount_key#23){++++}, at: [<ffffffff90b6358a>]
trylock_super+0x1a/0xe0 fs/super.c:402

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.81+ #6
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0xb9/0x11b lib/dump_stack.c:53
nmi_cpu_backtrace.cold.0+0x47/0x85 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x121/0x146 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline]
watchdog+0x574/0xa70 kernel/hung_task.c:252
kthread+0x348/0x420 kernel/kthread.c:232
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 17064 Comm: syz-executor2 Not tainted 4.14.81+ #6
task: ffff8801d6394680 task.stack: ffff8801c5878000
RIP: 0010:trace_lock_acquire include/trace/events/lock.h:13 [inline]
RIP: 0010:lock_acquire+0x221/0x380 kernel/locking/lockdep.c:3990
RSP: 0018:ffff8801c587f1c0 EFLAGS: 00000046
RAX: ffff8801d172d3d0 RBX: 0000000000000246 RCX: ffff8801d172d3d0
RDX: dffffc0000000000 RSI: 1ffff1003a2e5a7a RDI: ffff8801d6394eac
RBP: ffffffff92aceb60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000002 R15: 0000000000000000
FS: 00007f2404b94700(0000) GS:ffff8801dba00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000792b60 CR3: 00000001c7daa004 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
rcu_lock_acquire include/linux/rcupdate.h:244 [inline]
rcu_read_lock include/linux/rcupdate.h:631 [inline]
page_evictable+0x39/0x200 mm/vmscan.c:3967
shrink_active_list+0x44f/0xc80 mm/vmscan.c:2027
shrink_list mm/vmscan.c:2171 [inline]
shrink_node_memcg+0x641/0x12e0 mm/vmscan.c:2438
shrink_node+0x301/0xbf0 mm/vmscan.c:2630
shrink_zones mm/vmscan.c:2812 [inline]
do_try_to_free_pages+0x349/0xde0 mm/vmscan.c:2874
try_to_free_pages+0x204/0x6b0 mm/vmscan.c:3080
free_more_memory+0x8a/0xc0 fs/buffer.c:271
__getblk_slow fs/buffer.c:1107 [inline]
__getblk_gfp+0x533/0x720 fs/buffer.c:1382
__bread_gfp+0x28/0x1e0 fs/buffer.c:1416
sb_bread include/linux/buffer_head.h:307 [inline]
read_raw_super_block fs/f2fs/super.c:2830 [inline]
f2fs_fill_super+0x27d/0x5590 fs/f2fs/super.c:3058
mount_bdev+0x2ab/0x370 fs/super.c:1149
mount_fs+0x28f/0x31a fs/super.c:1255
vfs_kern_mount.part.9+0xce/0x4a0 fs/namespace.c:1056
vfs_kern_mount fs/namespace.c:1038 [inline]
do_new_mount fs/namespace.c:2561 [inline]
do_mount+0x404/0x26e0 fs/namespace.c:2891
SYSC_mount fs/namespace.c:3107 [inline]
SyS_mount+0xe5/0x100 fs/namespace.c:3084
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457569
RSP: 002b:00007f2404b93c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
RDX: 0000000020000100 RSI: 00000000200000c0 RDI: 0000000020000680
RBP: 000000000072bf00 R08: 0000000020000280 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2404b946d4
R13: 00000000004c2b0c R14: 00000000004d4260 R15: 00000000ffffffff
Code: 7d 62 02 00 0f 84 12 01 00 00 48 85 c9 0f 84 a4 00 00 00 48 ba 00 00
00 00 00 fc ff df 48 89 ce 48 89 c8 48 c1 ee 03 80 3c 16 00 <0f> 85 27 01
00 00 4c 8b 19 48 89 2c 24 48 89 c5 48 89 5c 24 08


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.