============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.9.1978/17691 is trying to acquire lock:
ffff888069d2b528 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_free_blocks fs/udf/balloc.c:375 [inline]
ffff888069d2b528 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_free_blocks+0x879/0x11c0 fs/udf/balloc.c:677

but task is already holding lock:
ffff888069d2b528 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_new_block fs/udf/balloc.c:581 [inline]
ffff888069d2b528 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_new_block+0x38f/0x1780 fs/udf/balloc.c:725

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

4 locks held by syz.9.1978/17691:
 #0: ffff8880511d6428 (sb_writers#20){.+.+}-{0:0}, at: splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
 #1: ffff888045faaf40 (&sb->s_type->i_mutex_key#25){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
 #1: ffff888045faaf40 (&sb->s_type->i_mutex_key#25){+.+.}-{4:4}, at: udf_file_write_iter+0x6d/0x7b0 fs/udf/file.c:95
 #2: ffff888045faad70 (&ei->i_data_sem#2){++++}-{4:4}, at: udf_map_block+0x159/0x5b0 fs/udf/inode.c:446
 #3: ffff888069d2b528 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_new_block fs/udf/balloc.c:581 [inline]
 #3: ffff888069d2b528 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_new_block+0x38f/0x1780 fs/udf/balloc.c:725

stack backtrace:
CPU: 1 UID: 0 PID: 17691 Comm: syz.9.1978 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x1133/0x1ce0 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
 udf_table_free_blocks fs/udf/balloc.c:375 [inline]
 udf_free_blocks+0x879/0x11c0 fs/udf/balloc.c:677
 udf_delete_aext+0x461/0xd80 fs/udf/inode.c:2380
 udf_table_new_block fs/udf/balloc.c:645 [inline]
 udf_new_block+0x1336/0x1780 fs/udf/balloc.c:725
 inode_getblk+0xc6f/0x40e0 fs/udf/inode.c:902
 udf_map_block+0x2dd/0x5b0 fs/udf/inode.c:454
 __udf_get_block+0x98/0x330 fs/udf/inode.c:468
 __block_write_begin_int+0x4f4/0x16d0 fs/buffer.c:2145
 block_write_begin+0x9a/0x1d0 fs/buffer.c:2256
 udf_write_begin+0x1e5/0x2a0 fs/udf/inode.c:262
 generic_perform_write+0x3c5/0x900 mm/filemap.c:4175
 __generic_file_write_iter+0x1f7/0x240 mm/filemap.c:4292
 udf_file_write_iter+0x233/0x7b0 fs/udf/file.c:111
 iter_file_splice_write+0xa24/0x12e0 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x192/0x6c0 fs/splice.c:1161
 splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x174/0x240 fs/splice.c:1230
 do_sendfile+0xb06/0xe50 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1417
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f302038ebe9
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:00007f301e5cd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f30205c6090 RCX: 00007f302038ebe9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f3020411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f30205c6128 R14: 00007f30205c6090 R15: 00007ffee37e5198
 </TASK>