======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc4-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.31/5766 is trying to acquire lock:
ffff8881416f80a8 (&q->q_usage_counter(io)#3){++++}-{0:0}, at: __submit_bio+0xba/0x190 block/blk-core.c:629

but task is already holding lock:
ffff88810cefd0e8 (&sbi->s_lock){+.+.}-{4:4}, at: exfat_create+0xed/0x220 fs/exfat/namei.c:553

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sbi->s_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x99/0x9a0 kernel/locking/mutex.c:752
       exfat_lookup+0xc9/0x540 fs/exfat/namei.c:701
       lookup_open fs/namei.c:3573 [inline]
       open_last_lookups fs/namei.c:3694 [inline]
       path_openat+0x5cd/0xdf0 fs/namei.c:3930
       do_filp_open+0xad/0x150 fs/namei.c:3960
       do_sys_openat2+0x7e/0xe0 fs/open.c:1415
       do_sys_open fs/open.c:1430 [inline]
       __do_sys_openat fs/open.c:1446 [inline]
       __se_sys_openat fs/open.c:1441 [inline]
       __x64_sys_openat+0x7c/0xa0 fs/open.c:1441
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xa0/0x180 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&sb->s_type->i_mutex_key#20){++++}-{4:4}:
       down_write+0x29/0xb0 kernel/locking/rwsem.c:1577
       inode_lock include/linux/fs.h:815 [inline]
       __generic_file_fsync+0x31/0x90 fs/libfs.c:1532
       exfat_file_fsync+0x26/0x60 fs/exfat/file.c:524
       __loop_update_dio+0x7a/0xf0 drivers/block/loop.c:204
       loop_set_status+0x19f/0x270 drivers/block/loop.c:1290
       lo_ioctl+0x636/0x930
       blkdev_ioctl+0x2ba/0x310 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:907 [inline]
       __se_sys_ioctl+0x6b/0xb0 fs/ioctl.c:893
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xa0/0x180 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&q->q_usage_counter(io)#3){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x1236/0x2570 kernel/locking/lockdep.c:5202
       lock_acquire+0xeb/0x270 kernel/locking/lockdep.c:5825
       bio_queue_enter block/blk.h:75 [inline]
       blk_mq_submit_bio+0x217/0x7f0 block/blk-mq.c:3069
       __submit_bio+0xba/0x190 block/blk-core.c:629
       __submit_bio_noacct_mq block/blk-core.c:710 [inline]
       submit_bio_noacct_nocheck+0x141/0x3d0 block/blk-core.c:739
       submit_bh fs/buffer.c:2824 [inline]
       __sync_dirty_buffer+0x9a/0xe0 fs/buffer.c:2862
       exfat_set_vol_flags fs/exfat/super.c:115 [inline]
       exfat_set_volume_dirty+0x59/0x70 fs/exfat/super.c:124
       exfat_create+0xf5/0x220 fs/exfat/namei.c:554
       lookup_open fs/namei.c:3595 [inline]
       open_last_lookups fs/namei.c:3694 [inline]
       path_openat+0x643/0xdf0 fs/namei.c:3930
       do_filp_open+0xad/0x150 fs/namei.c:3960
       do_sys_openat2+0x7e/0xe0 fs/open.c:1415
       do_sys_open fs/open.c:1430 [inline]
       __do_sys_openat fs/open.c:1446 [inline]
       __se_sys_openat fs/open.c:1441 [inline]
       __x64_sys_openat+0x7c/0xa0 fs/open.c:1441
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xa0/0x180 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &q->q_usage_counter(io)#3 --> &sb->s_type->i_mutex_key#20 --> &sbi->s_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sbi->s_lock);
                               lock(&sb->s_type->i_mutex_key#20);
                               lock(&sbi->s_lock);
  rlock(&q->q_usage_counter(io)#3);

 *** DEADLOCK ***

3 locks held by syz.0.31/5766:
 #0: ffff888109b68420 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x12/0x40 fs/namespace.c:515
 #1: ffff8881101dac68 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: inode_lock include/linux/fs.h:815 [inline]
 #1: ffff8881101dac68 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: open_last_lookups fs/namei.c:3691 [inline]
 #1: ffff8881101dac68 (&sb->s_type->i_mutex_key#20){++++}-{4:4}, at: path_openat+0x235/0xdf0 fs/namei.c:3930
 #2: ffff88810cefd0e8 (&sbi->s_lock){+.+.}-{4:4}, at: exfat_create+0xed/0x220 fs/exfat/namei.c:553

stack backtrace:
CPU: 0 UID: 0 PID: 5766 Comm: syz.0.31 Not tainted 6.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xa3/0x100 lib/dump_stack.c:120
 print_circular_bug+0x28d/0x2a0 kernel/locking/lockdep.c:2074
 check_noncircular+0x119/0x140 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x1236/0x2570 kernel/locking/lockdep.c:5202
 lock_acquire+0xeb/0x270 kernel/locking/lockdep.c:5825
 bio_queue_enter block/blk.h:75 [inline]
 blk_mq_submit_bio+0x217/0x7f0 block/blk-mq.c:3069
 __submit_bio+0xba/0x190 block/blk-core.c:629
 __submit_bio_noacct_mq block/blk-core.c:710 [inline]
 submit_bio_noacct_nocheck+0x141/0x3d0 block/blk-core.c:739
 submit_bh fs/buffer.c:2824 [inline]
 __sync_dirty_buffer+0x9a/0xe0 fs/buffer.c:2862
 exfat_set_vol_flags fs/exfat/super.c:115 [inline]
 exfat_set_volume_dirty+0x59/0x70 fs/exfat/super.c:124
 exfat_create+0xf5/0x220 fs/exfat/namei.c:554
 lookup_open fs/namei.c:3595 [inline]
 open_last_lookups fs/namei.c:3694 [inline]
 path_openat+0x643/0xdf0 fs/namei.c:3930
 do_filp_open+0xad/0x150 fs/namei.c:3960
 do_sys_openat2+0x7e/0xe0 fs/open.c:1415
 do_sys_open fs/open.c:1430 [inline]
 __do_sys_openat fs/open.c:1446 [inline]
 __se_sys_openat fs/open.c:1441 [inline]
 __x64_sys_openat+0x7c/0xa0 fs/open.c:1441
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xa0/0x180 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ae917e719
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ae9f1b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4ae9335f80 RCX: 00007f4ae917e719
RDX: 000000000000275a RSI: 0000000020000080 RDI: ffffffffffffff9c
RBP: 00007f4ae91f132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4ae9335f80 R15: 00007ffd5cb927f8
 </TASK>