============================================
WARNING: possible recursive locking detected
6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 Not tainted
--------------------------------------------
syz.0.0/5322 is trying to acquire lock:
ffff88803e1e9d28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_free_blocks fs/udf/balloc.c:375 [inline]
ffff88803e1e9d28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_free_blocks+0x9e2/0x17f0 fs/udf/balloc.c:677

but task is already holding lock:
ffff88803e1e9d28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
ffff88803e1e9d28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_prealloc_blocks+0x8d0/0x10b0 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

4 locks held by syz.0.0/5322:
 #0: ffff888042066420 (sb_writers#12){.+.+}-{0:0}, at: do_coredump+0x1e96/0x2a30 fs/coredump.c:758
 #1: ffff8880439e2280 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #1: ffff8880439e2280 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: udf_file_write_iter+0x6e/0x6c0 fs/udf/file.c:95
 #2: ffff8880439e20b0 (&ei->i_data_sem#2){++++}-{4:4}, at: udf_map_block+0x291/0x42a0 fs/udf/inode.c:439
 #3: ffff88803e1e9d28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
 #3: ffff88803e1e9d28 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_prealloc_blocks+0x8d0/0x10b0 fs/udf/balloc.c:701

stack backtrace:
CPU: 0 UID: 0 PID: 5322 Comm: syz.0.0 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #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_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3042
 check_deadlock kernel/locking/lockdep.c:3094 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3896
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
 udf_table_free_blocks fs/udf/balloc.c:375 [inline]
 udf_free_blocks+0x9e2/0x17f0 fs/udf/balloc.c:677
 udf_delete_aext+0x4df/0xbc0 fs/udf/inode.c:2373
 udf_table_prealloc_blocks fs/udf/balloc.c:543 [inline]
 udf_prealloc_blocks+0xb7e/0x10b0 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+0x1ddd/0x42a0 fs/udf/inode.c:447
 __udf_get_block+0x52/0x250 fs/udf/inode.c:461
 __block_write_begin_int+0x6b2/0x1900 fs/buffer.c:2151
 block_write_begin+0x8a/0x120 fs/buffer.c:2262
 udf_write_begin+0x100/0x260 fs/udf/inode.c:256
 generic_perform_write+0x2c4/0x910 mm/filemap.c:4103
 udf_file_write_iter+0x2d5/0x6c0 fs/udf/file.c:111
 __kernel_write_iter+0x390/0x860 fs/read_write.c:617
 dump_emit_page fs/coredump.c:885 [inline]
 dump_user_range+0x830/0xc20 fs/coredump.c:959
 elf_core_dump+0x32ed/0x3900 fs/binfmt_elf.c:2128
 do_coredump+0x1ec8/0x2a30 fs/coredump.c:759
 get_signal+0x10d9/0x1310 kernel/signal.c:3019
 arch_do_signal_or_restart+0x95/0x780 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 irqentry_exit_to_user_mode+0x81/0x120 kernel/entry/common.c:231
 exc_general_protection+0x171/0x200 arch/x86/kernel/traps.c:791
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617
RIP: 0033:0x7f654178e971
Code: 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 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:00002000000002c0 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f65419b6240 RCX: 00007f654178e969
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000000001000000
RBP: 00007f6541810ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f65419b6240 R15: 00007ffd39b8b4d8
 </TASK>