======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc4-next-20230120 #1 Not tainted
------------------------------------------------------
syz-executor.2/269 is trying to acquire lock:
ffff8880100763f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: __jbd2_log_wait_for_space+0x238/0x460

but task is already holding lock:
ffff88801c745d70 (&sb->s_type->i_mutex_key#6){++++}-{3:3}, at: vfs_unlink+0xd9/0x930

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#6){++++}-{3:3}:
       down_read+0x9c/0x450
       ext4_bmap+0x52/0x470
       bmap+0xb0/0x130
       jbd2_journal_bmap+0xac/0x190
       jbd2_journal_flush+0x860/0xc10
       __ext4_ioctl+0x9fd/0x42a0
       __x64_sys_ioctl+0x19e/0x210
       do_syscall_64+0x3f/0x90
       entry_SYSCALL_64_after_hwframe+0x72/0xdc

-> #0 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       __lock_acquire+0x2a52/0x5e90
       lock_acquire.part.0+0x120/0x340
       mutex_lock_io_nested+0x14c/0x1300
       __jbd2_log_wait_for_space+0x238/0x460
       add_transaction_credits+0xa42/0xb80
       start_this_handle+0x3ac/0x14c0
       jbd2__journal_start+0x394/0x6b0
       __ext4_journal_start_sb+0x4c2/0x6f0
       __ext4_unlink+0x44e/0xcf0
       ext4_unlink+0x3ac/0x640
       vfs_unlink+0x35e/0x930
       do_unlinkat+0x3b9/0x650
       __x64_sys_unlink+0xca/0x110
       do_syscall_64+0x3f/0x90
       entry_SYSCALL_64_after_hwframe+0x72/0xdc

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz-executor.2/269:
 #0: ffff888010072438 (sb_writers#3){.+.+}-{0:0}, at: do_unlinkat+0x190/0x650
 #1: ffff88801c743fa0 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0x280/0x650
 #2: ffff88801c745d70 (&sb->s_type->i_mutex_key#6){++++}-{3:3}, at: vfs_unlink+0xd9/0x930

stack backtrace:
CPU: 0 PID: 269 Comm: syz-executor.2 Not tainted 6.2.0-rc4-next-20230120 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x8f/0xb7
 check_noncircular+0x263/0x2e0
 __lock_acquire+0x2a52/0x5e90
 lock_acquire.part.0+0x120/0x340
 mutex_lock_io_nested+0x14c/0x1300
 __jbd2_log_wait_for_space+0x238/0x460
 add_transaction_credits+0xa42/0xb80
 start_this_handle+0x3ac/0x14c0
 jbd2__journal_start+0x394/0x6b0
 __ext4_journal_start_sb+0x4c2/0x6f0
 __ext4_unlink+0x44e/0xcf0
 ext4_unlink+0x3ac/0x640
 vfs_unlink+0x35e/0x930
 do_unlinkat+0x3b9/0x650
 __x64_sys_unlink+0xca/0x110
 do_syscall_64+0x3f/0x90
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7fbdddf07457
Code: 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 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:00007ffcc37a2408 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbdddf07457
RDX: 00007ffcc37a2440 RSI: 00007ffcc37a2440 RDI: 00007ffcc37a24d0
RBP: 00007ffcc37a24d0 R08: 0000000000000001 R09: 00007ffcc37a22a0
R10: 0000555556df5c9b R11: 0000000000000206 R12: 00007fbdddf61105
R13: 00007ffcc37a3590 R14: 0000555556df5c20 R15: 00007ffcc37a35d0
 </TASK>
mac80211_hwsim: wmediumd released netlink socket, switching to perfect channel medium
warning: checkpointing journal with EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT can be slow
warning: checkpointing journal with EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT can be slow
warning: checkpointing journal with EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT can be slow