loop4: detected capacity change from 0 to 2048
EXT4-fs (loop4): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.4.795/9096 is trying to acquire lock:
ffff8881bb6f80c0 (&ei->xattr_sem){++++}-{4:4}, at: ext4_destroy_inline_data+0x28/0xe0

but task is already holding lock:
ffff8881bd916c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x205/0x3b0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       percpu_down_read_internal+0x48/0x1c0
       ext4_writepages+0x205/0x3b0
       do_writepages+0x32e/0x550
       __writeback_single_inode+0x133/0x10e0
       writeback_single_inode+0x4ac/0xdc0
       write_inode_now+0x1c2/0x290
       iput+0x8c1/0xe80
       ext4_xattr_block_set+0x1fd4/0x2ad0
       ext4_expand_extra_isize_ea+0x12cf/0x1ea0
       __ext4_expand_extra_isize+0x30d/0x400
       __ext4_mark_inode_dirty+0x45c/0x710
       ext4_evict_inode+0x986/0x10e0
       evict+0x61e/0xb10
       ext4_orphan_cleanup+0xc38/0x1470
       ext4_fill_super+0x5a19/0x6330
       get_tree_bdev_flags+0x431/0x4f0
       vfs_get_tree+0x92/0x2a0
       do_new_mount+0x341/0xd30
       __se_sys_mount+0x31d/0x420
       do_syscall_64+0x174/0x580
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ei->xattr_sem){++++}-{4:4}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0x106/0x350
       down_write+0x96/0x200
       ext4_destroy_inline_data+0x28/0xe0
       ext4_do_writepages+0x51e/0x4670
       ext4_writepages+0x241/0x3b0
       do_writepages+0x32e/0x550
       filemap_flush+0x1e1/0x2e0
       ext4_release_file+0x82/0x310
       __fput+0x44f/0xa60
       task_work_run+0x1d9/0x270
       exit_to_user_mode_loop+0x193/0x680
       do_syscall_64+0x353/0x580
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&sbi->s_writepages_rwsem);
                               lock(&ei->xattr_sem);
                               lock(&sbi->s_writepages_rwsem);
  lock(&ei->xattr_sem);

 *** DEADLOCK ***

1 lock held by syz.4.795/9096:
 #0: ffff8881bd916c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x205/0x3b0

stack backtrace:
CPU: 1 UID: 0 PID: 9096 Comm: syz.4.795 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x15a5/0x2cf0
 lock_acquire+0x106/0x350
 down_write+0x96/0x200
 ext4_destroy_inline_data+0x28/0xe0
 ext4_do_writepages+0x51e/0x4670
 ext4_writepages+0x241/0x3b0
 do_writepages+0x32e/0x550
 filemap_flush+0x1e1/0x2e0
 ext4_release_file+0x82/0x310
 __fput+0x44f/0xa60
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0x193/0x680
 do_syscall_64+0x353/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff9e3d9ce59
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:00007ff9e4d2a028 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ff9e4015fa0 RCX: 00007ff9e3d9ce59
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000000
RBP: 00007ff9e3e32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff9e4016038 R14: 00007ff9e4015fa0 R15: 00007fff0758ba38
 </TASK>
EXT4-fs error (device loop4): ext4_mb_generate_buddy:1317: group 0, block bitmap and bg descriptor inconsistent: 25 vs 150994969 free clusters
EXT4-fs (loop4): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 28
EXT4-fs (loop4): This should not happen!! Data will be lost

EXT4-fs (loop4): Total free blocks count 0
EXT4-fs (loop4): Free/Dirty block details
EXT4-fs (loop4): free_blocks=2415919104
EXT4-fs (loop4): dirty_blocks=16
EXT4-fs (loop4): Block reservation details
EXT4-fs (loop4): i_reserved_data_blocks=1
