loop0: detected capacity change from 0 to 32768
=======================================================
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
XFS (loop0): Mounting V5 Filesystem bfdc47fc-10d8-4eed-a562-11a831b3f791
XFS (loop0): Ending clean mount
XFS (loop0): Quotacheck needed: Please wait.
XFS (loop0): Quotacheck: Done.

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.0/5318 is trying to acquire lock:
ffff8880524c2540 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_reclaim_inode fs/xfs/xfs_icache.c:1046 [inline]
ffff8880524c2540 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1738 [inline]
ffff8880524c2540 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_icwalk_ag+0x12b7/0x1980 fs/xfs/xfs_icache.c:1820

but task is already holding lock:
ffff8880524c16c0 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock_for_iomap fs/xfs/xfs_iomap.c:792 [inline]
ffff8880524c16c0 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_buffered_write_iomap_begin+0x674/0x2350 fs/xfs/xfs_iomap.c:1830

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&xfs_nondir_ilock_class);
  lock(&xfs_nondir_ilock_class);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

locks held by syz.0.0/5318: 4, last CPU#0:
 #0: ffff88801d230460 (sb_writers#11){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #0: ffff88801d230460 (sb_writers#11){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #1: ffff8880524c18d0 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: xfs_ilock+0xee/0x380 fs/xfs/xfs_inode.c:149
 #2: ffff8880524c16c0 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock_for_iomap fs/xfs/xfs_iomap.c:792 [inline]
 #2: ffff8880524c16c0 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_buffered_write_iomap_begin+0x674/0x2350 fs/xfs/xfs_iomap.c:1830
 #3: ffff88801d2300e8 (&type->s_umount_key#52){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:688 [inline]
 #3: ffff88801d2300e8 (&type->s_umount_key#52){.+.+}-{4:4}, at: super_cache_scan+0x94/0x500 fs/super.c:213

stack backtrace:
CPU: 0 UID: 0 PID: 5318 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+0x27a/0x290 kernel/locking/lockdep.c:3057
 check_deadlock kernel/locking/lockdep.c:3109 [inline]
 validate_chain kernel/locking/lockdep.c:3911 [inline]
 __lock_acquire+0x261c/0x2e50 kernel/locking/lockdep.c:5254
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
 down_write_nested+0x9d/0x210 kernel/locking/rwsem.c:1757
 xfs_reclaim_inode fs/xfs/xfs_icache.c:1046 [inline]
 xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1738 [inline]
 xfs_icwalk_ag+0x12b7/0x1980 fs/xfs/xfs_icache.c:1820
 xfs_icwalk fs/xfs/xfs_icache.c:1868 [inline]
 xfs_reclaim_inodes_nr+0x1e5/0x260 fs/xfs/xfs_icache.c:1112
 super_cache_scan+0x476/0x500 fs/super.c:244
 do_shrink_slab+0x6d0/0x10e0 mm/shrinker.c:443
 shrink_slab+0xea4/0x1220 mm/shrinker.c:674
 shrink_one+0x2a2/0x730 mm/vmscan.c:5119
 shrink_many mm/vmscan.c:5180 [inline]
 lru_gen_shrink_node mm/vmscan.c:5258 [inline]
 shrink_node+0x35d0/0x3e30 mm/vmscan.c:6247
 shrink_zones mm/vmscan.c:6503 [inline]
 do_try_to_free_pages+0x6a3/0x1990 mm/vmscan.c:6565
 try_to_free_pages+0x90a/0xe50 mm/vmscan.c:6804
 __perform_reclaim mm/page_alloc.c:4451 [inline]
 __alloc_pages_direct_reclaim+0x17d/0x360 mm/page_alloc.c:4478
 __alloc_pages_slowpath+0x64a/0xec0 mm/page_alloc.c:4939
 __alloc_frozen_pages_noprof+0x3f3/0x5a0 mm/page_alloc.c:5449
 alloc_pages_mpol+0x21e/0x390 mm/mempolicy.c:2486
 alloc_frozen_pages_noprof mm/mempolicy.c:2557 [inline]
 alloc_pages_noprof+0xb1/0x2b0 mm/mempolicy.c:2577
 stack_depot_save_flags+0x738/0x7f0 lib/stackdepot.c:685
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_node_track_caller_noprof+0x4b4/0x720 mm/slub.c:5545
 __do_krealloc mm/slub.c:6937 [inline]
 krealloc_node_align_noprof+0x19a/0x390 mm/slub.c:6958
 xfs_iext_realloc_root fs/xfs/libxfs/xfs_iext_tree.c:613 [inline]
 xfs_iext_insert_raw+0x13c/0x30a0 fs/xfs/libxfs/xfs_iext_tree.c:647
 xfs_iext_insert+0x36/0x230 fs/xfs/libxfs/xfs_iext_tree.c:684
 xfs_bmap_add_extent_hole_delay+0x4e8/0x850 fs/xfs/xfs_iomap.c:1443
 xfs_bmapi_reserve_delalloc+0xc60/0xdb0 fs/xfs/xfs_iomap.c:1562
 xfs_buffered_write_iomap_begin+0x18da/0x2350 fs/xfs/xfs_iomap.c:2078
 iomap_iter_next include/linux/iomap.h:382 [inline]
 xfs_buffered_write_iomap_next+0x52c/0x740 fs/xfs/xfs_iomap.c:2182
 iomap_iter+0xe2/0xec0 fs/iomap/iter.c:122
 iomap_file_buffered_write+0x980/0xb90 fs/iomap/buffered-io.c:1312
 xfs_file_buffered_write+0x20a/0x870 fs/xfs/xfs_file.c:1064
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_pwrite64 fs/read_write.c:794 [inline]
 __do_sys_pwrite64 fs/read_write.c:802 [inline]
 __se_sys_pwrite64 fs/read_write.c:799 [inline]
 __x64_sys_pwrite64+0x196/0x220 fs/read_write.c:799
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fac50b9e159
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:00007fac4cff4fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fac50e25fa0 RCX: 00007fac50b9e159
RDX: 00000000ffffff07 RSI: 0000200000000140 RDI: 0000000000000008
RBP: 00007fac50c35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fac50e26038 R14: 00007fac50e25fa0 R15: 00007ffd6ab0ea78
 </TASK>