ext4 filesystem being mounted at /483/file0aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa supports timestamps until 2038-01-19 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.1905/11504 is trying to acquire lock:
ffff8881156c0610 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x2d6/0xee0

but task is already holding lock:
ffff888173d66b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x2f3/0x1010

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       lock_acquire+0x120/0x360
       percpu_down_read_internal+0x48/0x1c0
       ext4_writepages+0x1cc/0x350
       do_writepages+0x32e/0x550
       __writeback_single_inode+0x145/0xff0
       writeback_single_inode+0x1f9/0x6a0
       write_inode_now+0x160/0x1d0
       iput+0x830/0xc50
       ext4_xattr_block_set+0x1fce/0x2ac0
       ext4_expand_extra_isize_ea+0x12da/0x1ea0
       __ext4_expand_extra_isize+0x30d/0x400
       __ext4_mark_inode_dirty+0x46c/0x700
       ext4_evict_inode+0x80d/0xee0
       evict+0x504/0x9c0
       ext4_orphan_cleanup+0xc20/0x1460
       ext4_fill_super+0x5920/0x61e0
       get_tree_bdev_flags+0x40e/0x4d0
       vfs_get_tree+0x92/0x2b0
       do_new_mount+0x302/0xa10
       __se_sys_mount+0x313/0x410
       do_syscall_64+0xfa/0xfa0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal){.+.+}-{0:0}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       percpu_down_read_internal+0x48/0x1c0
       ext4_evict_inode+0x2d6/0xee0
       evict+0x504/0x9c0
       ext4_ext_migrate+0xd23/0x1010
       ext4_ioctl+0x204b/0x48e0
       __se_sys_ioctl+0xfc/0x170
       do_syscall_64+0xfa/0xfa0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.4.1905/11504:
 #0: ffff8881156c0420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200
 #1: ffff88801d2ba090 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: ext4_ioctl+0x2043/0x48e0
 #2: ffff888173d66b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x2f3/0x1010

stack backtrace:
CPU: 0 UID: 0 PID: 11504 Comm: syz.4.1905 Not tainted syzkaller #0 PREEMPT(full) 
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+0x189/0x250
 print_circular_bug+0x2ee/0x310
 check_noncircular+0x134/0x160
 validate_chain+0xb9b/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 percpu_down_read_internal+0x48/0x1c0
 ext4_evict_inode+0x2d6/0xee0
 evict+0x504/0x9c0
 ext4_ext_migrate+0xd23/0x1010
 ext4_ioctl+0x204b/0x48e0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc33798f7c9
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:00007fc338913038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc337be5fa0 RCX: 00007fc33798f7c9
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007fc3379f297f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc337be6038 R14: 00007fc337be5fa0 R15: 00007ffd5e54ebe8
 </TASK>
