warning: checkpointing journal with EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT can be slow
======================================================
WARNING: possible circular locking dependency detected
6.2.0-syzkaller-13008-gdb47fa2e4cbf #0 Not tainted
------------------------------------------------------
syz-executor.5/10598 is trying to acquire lock:
ffff888144c68400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:768 [inline]
ffff888144c68400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_bmap+0x52/0x470 fs/ext4/inode.c:3242

but task is already holding lock:
ffff88814b8be3f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x47f/0xc90 fs/jbd2/journal.c:2473

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       mutex_lock_io_nested+0x143/0x11a0 kernel/locking/mutex.c:833
       __jbd2_log_wait_for_space+0x238/0x4b0 fs/jbd2/checkpoint.c:110
       add_transaction_credits+0xa2d/0xb70 fs/jbd2/transaction.c:298
       start_this_handle+0x3ae/0x14e0 fs/jbd2/transaction.c:422
       jbd2__journal_start+0x39d/0x9d0 fs/jbd2/transaction.c:520
       __ext4_journal_start_sb+0x706/0x890 fs/ext4/ext4_jbd2.c:111
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_handle_inode_extension+0x314/0x890 fs/ext4/file.c:340
       ext4_dio_write_iter fs/ext4/file.c:594 [inline]
       ext4_file_write_iter+0x1268/0x1710 fs/ext4/file.c:698
       call_write_iter include/linux/fs.h:1851 [inline]
       do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:735
       do_iter_write+0x182/0x700 fs/read_write.c:861
       vfs_iter_write+0x74/0xa0 fs/read_write.c:902
       iter_file_splice_write+0x743/0xc80 fs/splice.c:778
       do_splice_from fs/splice.c:856 [inline]
       direct_splice_actor+0x114/0x180 fs/splice.c:1023
       splice_direct_to_actor+0x335/0x8a0 fs/splice.c:978
       do_splice_direct+0x1ab/0x280 fs/splice.c:1066
       do_sendfile+0xb19/0x12c0 fs/read_write.c:1255
       __do_sys_sendfile64 fs/read_write.c:1323 [inline]
       __se_sys_sendfile64 fs/read_write.c:1309 [inline]
       __x64_sys_sendfile64+0x1d0/0x210 fs/read_write.c:1309
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3098 [inline]
       check_prevs_add kernel/locking/lockdep.c:3217 [inline]
       validate_chain kernel/locking/lockdep.c:3832 [inline]
       __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
       lock_acquire kernel/locking/lockdep.c:5669 [inline]
       lock_acquire+0x1e3/0x670 kernel/locking/lockdep.c:5634
       down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
       inode_lock_shared include/linux/fs.h:768 [inline]
       ext4_bmap+0x52/0x470 fs/ext4/inode.c:3242
       bmap+0xae/0x120 fs/inode.c:1799
       jbd2_journal_bmap+0xac/0x1c0 fs/jbd2/journal.c:976
       __jbd2_journal_erase fs/jbd2/journal.c:1788 [inline]
       jbd2_journal_flush+0x87b/0xc90 fs/jbd2/journal.c:2491
       ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline]
       __ext4_ioctl+0xb3f/0x4c90 fs/ext4/ioctl.c:1590
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&journal->j_checkpoint_mutex);
                               lock(&sb->s_type->i_mutex_key#8);
                               lock(&journal->j_checkpoint_mutex);
  lock(&sb->s_type->i_mutex_key#8);

 *** DEADLOCK ***

2 locks held by syz-executor.5/10598:
 #0: ffff88814b8be170 (&journal->j_barrier){+.+.}-{3:3}, at: jbd2_journal_lock_updates+0x162/0x310 fs/jbd2/transaction.c:904
 #1: ffff88814b8be3f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x47f/0xc90 fs/jbd2/journal.c:2473

stack backtrace:
CPU: 1 PID: 10598 Comm: syz-executor.5 Not tainted 6.2.0-syzkaller-13008-gdb47fa2e4cbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3098 [inline]
 check_prevs_add kernel/locking/lockdep.c:3217 [inline]
 validate_chain kernel/locking/lockdep.c:3832 [inline]
 __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
 lock_acquire kernel/locking/lockdep.c:5669 [inline]
 lock_acquire+0x1e3/0x670 kernel/locking/lockdep.c:5634
 down_read+0x3d/0x50 kernel/locking/rwsem.c:1520
 inode_lock_shared include/linux/fs.h:768 [inline]
 ext4_bmap+0x52/0x470 fs/ext4/inode.c:3242
 bmap+0xae/0x120 fs/inode.c:1799
 jbd2_journal_bmap+0xac/0x1c0 fs/jbd2/journal.c:976
 __jbd2_journal_erase fs/jbd2/journal.c:1788 [inline]
 jbd2_journal_flush+0x87b/0xc90 fs/jbd2/journal.c:2491
 ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline]
 __ext4_ioctl+0xb3f/0x4c90 fs/ext4/ioctl.c:1590
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f4489e8c0f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f448ab32168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4489fabf80 RCX: 00007f4489e8c0f9
RDX: 0000000020000000 RSI: 000000004004662b RDI: 0000000000000003
RBP: 00007f4489ee7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff6057195f R14: 00007f448ab32300 R15: 0000000000022000
 </TASK>