loop0: detected capacity change from 0 to 256
FAT-fs (loop0): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
======================================================
WARNING: possible circular locking dependency detected
6.0.0-rc3-next-20220829 #1 Not tainted
------------------------------------------------------
syz-executor.1/6766 is trying to acquire lock:
ffff888008018400 (&sb->s_type->i_mutex_key#6){++++}-{3:3}, at: ext4_bmap+0x4e/0x470

but task is already holding lock:
ffff8880100a23f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x48b/0xc00

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       mutex_lock_io_nested+0x148/0x1310
       jbd2_journal_flush+0x19a/0xc00
       ext4_ioctl_group_add+0x2b3/0x580
       __ext4_ioctl+0x6c7/0x4090
       __x64_sys_ioctl+0x19a/0x210
       do_syscall_64+0x3b/0x90
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (&journal->j_barrier){+.+.}-{3:3}:
       __mutex_lock+0x136/0x14d0
       jbd2_journal_lock_updates+0x15e/0x310
       ext4_change_inode_journal_flag+0x17f/0x530
       ext4_fileattr_set+0x140d/0x18a0
       vfs_fileattr_set+0x77c/0xb80
       do_vfs_ioctl+0xfc2/0x1610
       __x64_sys_ioctl+0x10c/0x210
       do_syscall_64+0x3b/0x90
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       ext4_writepages+0x1d2/0x3690
       do_writepages+0x1b0/0x6a0
       filemap_fdatawrite_wbc+0x147/0x1b0
       __filemap_fdatawrite_range+0xb6/0x100
       filemap_write_and_wait_range+0x89/0x110
       __iomap_dio_rw+0x5ed/0x1bd0
       iomap_dio_rw+0x3c/0xa0
       ext4_file_read_iter+0x268/0x400
       do_iter_readv_writev+0x2f0/0x3c0
       do_iter_read+0x2fb/0x750
       vfs_readv+0xe5/0x160
       do_readv+0x133/0x300
       do_syscall_64+0x3b/0x90
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sb->s_type->i_mutex_key#6){++++}-{3:3}:
       __lock_acquire+0x2a02/0x5e70
       lock_acquire+0x1a2/0x530
       down_read+0x98/0x450
       ext4_bmap+0x4e/0x470
       bmap+0xac/0x120
       jbd2_journal_bmap+0xa8/0x180
       jbd2_journal_flush+0x853/0xc00
       __ext4_ioctl+0x9e9/0x4090
       __x64_sys_ioctl+0x19a/0x210
       do_syscall_64+0x3b/0x90
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  &sb->s_type->i_mutex_key#6 --> &journal->j_barrier --> &journal->j_checkpoint_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&journal->j_checkpoint_mutex);
                               lock(&journal->j_barrier);
                               lock(&journal->j_checkpoint_mutex);
  lock(&sb->s_type->i_mutex_key#6);

 *** DEADLOCK ***

2 locks held by syz-executor.1/6766:
 #0: ffff8880100a2170 (&journal->j_barrier){+.+.}-{3:3}, at: jbd2_journal_lock_updates+0x15e/0x310
 #1: ffff8880100a23f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x48b/0xc00

stack backtrace:
CPU: 1 PID: 6766 Comm: syz-executor.1 Not tainted 6.0.0-rc3-next-20220829 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x8b/0xb3
 check_noncircular+0x263/0x2e0
 __lock_acquire+0x2a02/0x5e70
 lock_acquire+0x1a2/0x530
 down_read+0x98/0x450
 ext4_bmap+0x4e/0x470
 bmap+0xac/0x120
 jbd2_journal_bmap+0xa8/0x180
 jbd2_journal_flush+0x853/0xc00
 __ext4_ioctl+0x9e9/0x4090
 __x64_sys_ioctl+0x19a/0x210
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd45c7a5b19
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd459d1b188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd45c8b8f60 RCX: 00007fd45c7a5b19
RDX: 0000000020000440 RSI: 000000004004662b RDI: 0000000000000003
RBP: 00007fd45c7fff6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff3f8cc09f R14: 00007fd459d1b300 R15: 0000000000022000
 </TASK>
Process accounting resumed
Process accounting resumed