============================================
WARNING: possible recursive locking detected
6.15.0-rc2-syzkaller-00048-gc62f4b82d571 #0 Not tainted
--------------------------------------------
syz.0.0/5325 is trying to acquire lock:
ffff88803f03cd28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_free_blocks fs/udf/balloc.c:375 [inline]
ffff88803f03cd28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_free_blocks+0xa28/0x22b0 fs/udf/balloc.c:677

but task is already holding lock:
ffff88803f03cd28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
ffff88803f03cd28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_prealloc_blocks+0x864/0x1470 fs/udf/balloc.c:701

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sbi->s_alloc_mutex);
  lock(&sbi->s_alloc_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.0.0/5325:
 #0: ffff88801217a0f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x310 fs/file.c:1213
 #1: ffff888053566420 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3041 [inline]
 #1: ffff888053566420 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x23f/0xd10 fs/read_write.c:680
 #2: ffff888052d05c20 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #2: ffff888052d05c20 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: udf_file_write_iter+0x6d/0x6c0 fs/udf/file.c:95
 #3: ffff888052d05a50 (&ei->i_data_sem#2){++++}-{4:4}, at: udf_map_block+0x3b9/0x55c0 fs/udf/inode.c:439
 #4: ffff88803f03cd28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
 #4: ffff88803f03cd28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_prealloc_blocks+0x864/0x1470 fs/udf/balloc.c:701

stack backtrace:
CPU: 0 UID: 0 PID: 5325 Comm: syz.0.0 Not tainted 6.15.0-rc2-syzkaller-00048-gc62f4b82d571 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x2be/0x2d0 kernel/locking/lockdep.c:3042
 check_deadlock kernel/locking/lockdep.c:3094 [inline]
 validate_chain+0x928/0x24e0 kernel/locking/lockdep.c:3896
 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746
 udf_table_free_blocks fs/udf/balloc.c:375 [inline]
 udf_free_blocks+0xa28/0x22b0 fs/udf/balloc.c:677
 udf_delete_aext+0x6f3/0xec0 fs/udf/inode.c:2373
 udf_table_prealloc_blocks fs/udf/balloc.c:543 [inline]
 udf_prealloc_blocks+0xd04/0x1470 fs/udf/balloc.c:701
 udf_prealloc_extents fs/udf/inode.c:1053 [inline]
 inode_getblk fs/udf/inode.c:911 [inline]
 udf_map_block+0x2827/0x55c0 fs/udf/inode.c:447
 __udf_get_block+0x128/0x410 fs/udf/inode.c:461
 __block_write_begin_int+0x691/0x1930 fs/buffer.c:2116
 block_write_begin+0x8f/0x120 fs/buffer.c:2227
 udf_write_begin+0xfc/0x250 fs/udf/inode.c:256
 generic_perform_write+0x329/0xa10 mm/filemap.c:4102
 udf_file_write_iter+0x2e7/0x6c0 fs/udf/file.c:111
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x70f/0xd10 fs/read_write.c:684
 ksys_write+0x19d/0x2d0 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f501178e169
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:00007f5012550038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f50119b6080 RCX: 00007f501178e169
RDX: 000000000208e24b RSI: 0000200000000380 RDI: 000000000000000c
RBP: 00007f5011810a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f50119b6080 R15: 00007fffb75e2208
 </TASK>