task hung in gfs2_glock_nq on v7.2-rc3

[CJ <firefly0158@163.com>]

Hi,


syzbot reported "INFO: task hung in gfs2_glock_nq" on linux-5.15. The same
failure is still reproducible on v7.2-rc3 with the reproducer below.


Tested kernel:
  Linux v7.2-rc3
  HEAD a13c140cc289c0b7b3770bce5b3ad42ab35074aa


Observed failure:
Call Trace:
<TASK>
__schedule+0x1379/0x4ab0
schedule+0xd2/0x260
bit_wait+0x15/0xe0
__wait_on_bit+0xc9/0x190
out_of_line_wait_on_bit+0xd7/0x110
gfs2_glock_wait+0xaf/0x240
gfs2_glock_nq+0xadc/0x1ca0
__gfs2_lookup+0x105/0x290
__lookup_slow+0x15f/0x340
lookup_slow+0x51/0x80
path_lookupat.isra.0+0x619/0xbb0
filename_lookup+0x213/0x480
user_path_at+0x40/0x60
ksys_umount+0xb7/0x130
__x64_sys_umount+0x54/0x80
do_syscall_64+0xc4/0x6a0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fd3a8dafebb
</TASK>


The console does not identify the lock or page owner, so this is a report of a still-reproducible hang rather than a bisected root cause.


This is a report of a still-reproducible failure, not a bisected root cause.


Reproducer:
  SYZ reproducer: https://pastebin.com/raw/w0UwMrpB


Artifacts:
  console: https://pastebin.com/raw/1NSff3Yy
  kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=78ce1ad3d91bc375


Thanks.