syzbot

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.2.19/6020 is trying to acquire lock:
ffff88805a8d5128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_free_blocks fs/udf/balloc.c:392 [inline]
ffff88805a8d5128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_free_blocks+0x8ff/0x16e0 fs/udf/balloc.c:694

but task is already holding lock:
ffff88805a8d5128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_new_block fs/udf/balloc.c:598 [inline]
ffff88805a8d5128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_new_block+0xea7/0x1a70 fs/udf/balloc.c:742

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.2.19/6020:
 #0: ffff88807ebfe418 (sb_writers#13){.+.+}-{0:0}, at: do_sendfile+0x5b9/0xf70 fs/read_write.c:1253
 #1: ffff888058668f88 (&sb->s_type->i_mutex_key#20){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff888058668f88 (&sb->s_type->i_mutex_key#20){+.+.}-{3:3}, at: udf_file_write_iter+0x6e/0x620 fs/udf/file.c:95
 #2: ffff888058668da0 (&ei->i_data_sem#2){++++}-{3:3}, at: udf_map_block+0x284/0x4500 fs/udf/inode.c:443
 #3: ffff88805a8d5128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_new_block fs/udf/balloc.c:598 [inline]
 #3: ffff88805a8d5128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_new_block+0xea7/0x1a70 fs/udf/balloc.c:742

stack backtrace:
CPU: 0 PID: 6020 Comm: syz.2.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x5d40/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 udf_table_free_blocks fs/udf/balloc.c:392 [inline]
 udf_free_blocks+0x8ff/0x16e0 fs/udf/balloc.c:694
 udf_delete_aext+0x4e0/0xbc0 fs/udf/inode.c:2376
 udf_table_new_block fs/udf/balloc.c:662 [inline]
 udf_new_block+0x12fa/0x1a70 fs/udf/balloc.c:742
 inode_getblk fs/udf/inode.c:899 [inline]
 udf_map_block+0x1389/0x4500 fs/udf/inode.c:451
 __udf_get_block+0x53/0x250 fs/udf/inode.c:465
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 __block_write_begin fs/buffer.c:2173 [inline]
 block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
 udf_write_begin+0x1c0/0x430 fs/udf/inode.c:261
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 udf_file_write_iter+0x2c0/0x620 fs/udf/file.c:111
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x79a/0xc70 fs/read_write.c:860
 iter_file_splice_write+0x66f/0xc50 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0xe8/0x130 fs/splice.c:1142
 splice_direct_to_actor+0x2f0/0x870 fs/splice.c:1088
 do_splice_direct+0x1b7/0x2c0 fs/splice.c:1194
 do_sendfile+0x5dc/0xf70 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64+0x13f/0x190 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f965ad8f749
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:00007f965bca1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f965afe6090 RCX: 00007f965ad8f749
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f965ae13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f965afe6128 R14: 00007f965afe6090 R15: 00007ffffbd4f908
 </TASK>