possible deadlock in ext4_writepages on v7.2-rc3

possible deadlock in ext4_writepages on v7.2-rc3

[CJ]

Hi,


syzbot reported "possible deadlock in ext4_writepages" on linux-6.6. The same
failure is still reproducible on v7.2-rc3 with the reproducer below.


Tested kernel:
  Linux v7.2-rc3
  HEAD a13c140cc289c0b7b3770bce5b3ad42ab35074aa


Observed failure:
ffff888058b29380 (&ei->xattr_sem){++++}-{4:4}, at: __ext4_mark_inode_dirty+0x5c6/0x860
lock_acquire+0x1a4/0x350
down_write+0x91/0x200
ext4_destroy_inline_data+0x2d/0xe0
ext4_do_writepages+0x6bd/0x3e70
ext4_writepages+0x371/0x770
do_writepages+0x241/0x5b0
filemap_writeback+0x227/0x2d0
file_write_and_wait_range+0xcf/0x140
mmb_fsync_noflush+0x71/0x2d0
ext4_fsync_nojournal+0xe2/0x420
ext4_sync_file+0x8f9/0xb90
vfs_fsync_range+0x9e/0x190
ext4_buffered_write_iter+0x2d1/0x3b0
ext4_file_write_iter+0x5a3/0x1ab0
do_iter_readv_writev+0x655/0x9e0
vfs_writev+0x30c/0xd30
do_pwritev+0x1a6/0x270
__x64_sys_pwritev2+0xef/0x160
do_syscall_64+0xc4/0x7a0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
check_prev_add+0xe9/0xe30






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


Reproducer:
  SYZ reproducer: https://pastebin.com/raw/69vgAB5c


Artifacts:
  console: https://pastebin.com/raw/2Eh3hPz8
  kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=938110aa66424b94


Thanks.