======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc7-syzkaller-17891-geaed33698e35 #0 Not tainted
------------------------------------------------------
syz-executor.3/4652 is trying to acquire lock:
ffff0000c81703f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: __jbd2_log_wait_for_space+0xb8/0x310

but task is already holding lock:
ffff0000d07c8d90 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_buffered_write_iter+0x50/0x294

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
       down_read+0x5c/0x78
       ext4_bmap+0x34/0x1bc
       bmap+0x40/0x6c
       jbd2_journal_flush+0x2a4/0x554
       ext4_ioctl+0x2568/0x37bc
       __arm64_sys_ioctl+0xd0/0x148
       invoke_syscall+0x64/0x178
       el0_svc_common+0xbc/0x180
       do_el0_svc+0x48/0x110
       el0_svc+0x58/0x14c
       el0t_64_sync_handler+0x84/0xf0
       el0t_64_sync+0x190/0x194

-> #0 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
       __lock_acquire+0x1670/0x2f48
       lock_acquire+0x164/0x334
       __mutex_lock_common+0xd4/0xf64
       mutex_lock_io_nested+0x6c/0x88
       __jbd2_log_wait_for_space+0xb8/0x310
       add_transaction_credits+0x4a4/0x5f4
       start_this_handle+0x2b0/0x810
       jbd2__journal_start+0x148/0x1f0
       __ext4_journal_start_sb+0x2f8/0x664
       ext4_dirty_inode+0x44/0x9c
       __mark_inode_dirty+0x2cc/0xcd0
       generic_write_end+0x170/0x400
       ext4_da_write_end+0x444/0x5b8
       generic_perform_write+0x164/0x2b4
       ext4_buffered_write_iter+0x15c/0x294
       ext4_file_write_iter+0x98/0xc3c
       __kernel_write_iter+0xd8/0x27c
       dump_user_range+0x17c/0x3d4
       elf_core_dump+0x157c/0x1690
       do_coredump+0xaa4/0x11f8
       get_signal+0x9a4/0xd60
       do_notify_resume+0x180/0x2628
       el0_da+0xb8/0x168
       el0t_64_sync_handler+0xcc/0xf0
       el0t_64_sync+0x190/0x194

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

2 locks held by syz-executor.3/4652:
 #0: ffff0000c413e460 (sb_writers#3){.+.+}-{0:0}, at: do_coredump+0xa98/0x11f8
 #1: ffff0000d07c8d90 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_buffered_write_iter+0x50/0x294

stack backtrace:
CPU: 1 PID: 4652 Comm: syz-executor.3 Not tainted 6.2.0-rc7-syzkaller-17891-geaed33698e35 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
Call trace:
 dump_backtrace+0x1c8/0x1f4
 show_stack+0x2c/0x3c
 dump_stack_lvl+0xd0/0x124
 dump_stack+0x1c/0x28
 print_circular_bug+0x2c4/0x2c8
 check_noncircular+0x148/0x150
 __lock_acquire+0x1670/0x2f48
 lock_acquire+0x164/0x334
 __mutex_lock_common+0xd4/0xf64
 mutex_lock_io_nested+0x6c/0x88
 __jbd2_log_wait_for_space+0xb8/0x310
 add_transaction_credits+0x4a4/0x5f4
 start_this_handle+0x2b0/0x810
 jbd2__journal_start+0x148/0x1f0
 __ext4_journal_start_sb+0x2f8/0x664
 ext4_dirty_inode+0x44/0x9c
 __mark_inode_dirty+0x2cc/0xcd0
 generic_write_end+0x170/0x400
 ext4_da_write_end+0x444/0x5b8
 generic_perform_write+0x164/0x2b4
 ext4_buffered_write_iter+0x15c/0x294
 ext4_file_write_iter+0x98/0xc3c
 __kernel_write_iter+0xd8/0x27c
 dump_user_range+0x17c/0x3d4
 elf_core_dump+0x157c/0x1690
 do_coredump+0xaa4/0x11f8
 get_signal+0x9a4/0xd60
 do_notify_resume+0x180/0x2628
 el0_da+0xb8/0x168
 el0t_64_sync_handler+0xcc/0xf0
 el0t_64_sync+0x190/0x194