============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.15/4993 is trying to acquire lock:
ffff88801cf26d28 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_free_blocks fs/udf/balloc.c:396 [inline]
ffff88801cf26d28 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_free_blocks+0x9a0/0x17f0 fs/udf/balloc.c:687

but task is already holding lock:
ffff88801cf26d28 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_new_block fs/udf/balloc.c:595 [inline]
ffff88801cf26d28 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_new_block+0xe15/0x1990 fs/udf/balloc.c:735

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.0.15/4993:
 #0: ffff8880764ce460 (sb_writers#13){.+.+}-{0:0}, at: do_sendfile+0x4f6/0xe20 fs/read_write.c:1254
 #1: ffff88806dbd0f78 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:764 [inline]
 #1: ffff88806dbd0f78 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: udf_file_write_iter+0x6e/0x620 fs/udf/file.c:145
 #2: ffff88806dbd0da0 (&ei->i_data_sem#2){++++}-{3:3}, at: udf_get_block+0xff/0x41a0 fs/udf/inode.c:346
 #3: ffff88801cf26d28 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_new_block fs/udf/balloc.c:595 [inline]
 #3: ffff88801cf26d28 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_new_block+0xe15/0x1990 fs/udf/balloc.c:735

stack backtrace:
CPU: 0 PID: 4993 Comm: syz.0.15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3090 [inline]
 validate_chain kernel/locking/lockdep.c:3884 [inline]
 __lock_acquire+0x690e/0x7ea0 kernel/locking/lockdep.c:5171
 lock_acquire+0x1bc/0x4a0 kernel/locking/lockdep.c:5790
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747
 udf_table_free_blocks fs/udf/balloc.c:396 [inline]
 udf_free_blocks+0x9a0/0x17f0 fs/udf/balloc.c:687
 udf_delete_aext+0x4c4/0xba0 fs/udf/inode.c:2210
 udf_table_new_block fs/udf/balloc.c:655 [inline]
 udf_new_block+0x122f/0x1990 fs/udf/balloc.c:735
 inode_getblk fs/udf/inode.c:746 [inline]
 udf_get_block+0x11df/0x41a0 fs/udf/inode.c:359
 __block_write_begin_int+0x577/0x1ab0 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x96/0x1e0 fs/buffer.c:2102
 udf_write_begin+0x31/0x70 fs/udf/inode.c:212
 generic_perform_write+0x2fa/0x5c0 mm/filemap.c:3862
 __generic_file_write_iter+0x1fb/0x2a0 mm/filemap.c:3956
 udf_file_write_iter+0x284/0x620 fs/udf/file.c:164
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x638/0xb10 fs/read_write.c:861
 iter_file_splice_write+0x6be/0xcf0 fs/splice.c:685
 do_splice_from fs/splice.c:763 [inline]
 direct_splice_actor+0xe1/0x130 fs/splice.c:950
 splice_direct_to_actor+0x4b8/0xbd0 fs/splice.c:896
 do_splice_direct+0x1ce/0x2f0 fs/splice.c:1002
 do_sendfile+0x51b/0xe20 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64+0x141/0x1a0 fs/read_write.c:1309
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f768938a029
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f768a20e058 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f7689555fa0 RCX: 00007f768938a029
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000005
RBP: 00007f768940da05 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000800000009 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7689555fa0 R15: 00007fff1e59caa8
 </TASK>