============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.0/5332 is trying to acquire lock:
ffff88803447dd20 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_free_blocks fs/udf/balloc.c:375 [inline]
ffff88803447dd20 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_free_blocks+0xaaf/0x1940 fs/udf/balloc.c:677

but task is already holding lock:
ffff88803447dd20 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
ffff88803447dd20 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_prealloc_blocks+0x8f6/0x1130 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.0.0/5332:
 #0: ffff888011c48f78 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:601 [inline]
 #0: ffff888011c48f78 (&mm->mmap_lock){++++}-{4:4}, at: __get_user_pages_locked mm/gup.c:1744 [inline]
 #0: ffff888011c48f78 (&mm->mmap_lock){++++}-{4:4}, at: __gup_longterm_locked+0x108e/0x1630 mm/gup.c:2476
 #1: ffff888012266508 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3684
 #2: ffff888047adb7c0 (mapping.invalidate_lock#3){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1094 [inline]
 #2: ffff888047adb7c0 (mapping.invalidate_lock#3){++++}-{4:4}, at: udf_page_mkwrite+0x26f/0x7c0 fs/udf/file.c:51
 #3: ffff888047adb408 (&ei->i_data_sem#2){++++}-{4:4}, at: udf_map_block+0x2a4/0x42d0 fs/udf/inode.c:445
 #4: ffff88803447dd20 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
 #4: ffff88803447dd20 (&sbi->s_alloc_mutex){+.+.}-{4:4}, at: udf_prealloc_blocks+0x8f6/0x1130 fs/udf/balloc.c:701

stack backtrace:
CPU: 0 UID: 0 PID: 5332 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x1a3/0x1550 kernel/locking/mutex.c:820
 udf_table_free_blocks fs/udf/balloc.c:375 [inline]
 udf_free_blocks+0xaaf/0x1940 fs/udf/balloc.c:677
 udf_delete_aext+0x4fb/0xbe0 fs/udf/inode.c:2381
 udf_table_prealloc_blocks fs/udf/balloc.c:543 [inline]
 udf_prealloc_blocks+0xbd3/0x1130 fs/udf/balloc.c:701
 udf_prealloc_extents fs/udf/inode.c:1058 [inline]
 inode_getblk fs/udf/inode.c:916 [inline]
 udf_map_block+0x1e55/0x42d0 fs/udf/inode.c:453
 __udf_get_block+0x52/0x250 fs/udf/inode.c:467
 __block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2042
 udf_page_mkwrite+0x5b4/0x7c0 fs/udf/file.c:66
 do_page_mkwrite+0x14d/0x310 mm/memory.c:3684
 wp_page_shared mm/memory.c:4085 [inline]
 do_wp_page+0x19ba/0x4cc0 mm/memory.c:4304
 handle_pte_fault mm/memory.c:6443 [inline]
 __handle_mm_fault mm/memory.c:6565 [inline]
 handle_mm_fault+0x1698/0x3170 mm/memory.c:6734
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x167f/0x2730 mm/gup.c:1428
 __get_user_pages_locked mm/gup.c:1692 [inline]
 __gup_longterm_locked+0x1221/0x1630 mm/gup.c:2476
 gup_fast_fallback+0x1d84/0x20d0 mm/gup.c:3209
 iov_iter_extract_user_pages lib/iov_iter.c:1763 [inline]
 iov_iter_extract_pages+0x37b/0x5f0 lib/iov_iter.c:1826
 iov_iter_extract_bvecs+0xb1/0x920 lib/iov_iter.c:1917
 bio_iov_iter_get_pages+0x346/0x930 block/bio.c:1266
 blkdev_iov_iter_get_pages block/fops.c:49 [inline]
 __blkdev_direct_IO+0x677/0xfa0 block/fops.c:219
 blkdev_direct_IO+0x121a/0x1790 block/fops.c:436
 blkdev_read_iter+0x23d/0x440 block/fops.c:839
 aio_read+0x33a/0x4d0 fs/aio.c:1657
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0x79d/0x14c0 fs/aio.c:2107
 __do_sys_io_submit fs/aio.c:2166 [inline]
 __se_sys_io_submit+0x195/0x340 fs/aio.c:2136
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f00eb19ce59
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:00007f00ebfa0fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007f00eb416090 RCX: 00007f00eb19ce59
RDX: 00002000000000c0 RSI: 00000000000000ca RDI: 00007f00ebf5f000
RBP: 00007f00eb232d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f00eb416128 R14: 00007f00eb416090 R15: 00007fff38593308
 </TASK>