======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.979/8376 is trying to acquire lock:
ffff88810cf36770 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x426/0x10e0

but task is already holding lock:
ffff888116cd8cd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x308/0x1130

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+0x48/0x1d0
       ext4_writepages+0x205/0x3b0
       do_writepages+0x32e/0x550
       __writeback_single_inode+0x133/0x10e0
       writeback_single_inode+0x488/0xd60
       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+0x59bb/0x62d0
       get_tree_bdev_flags+0x431/0x4f0
       vfs_get_tree+0x92/0x2a0
       do_new_mount+0x341/0xd30
       __se_sys_mount+0x31d/0x420
       do_syscall_64+0x15f/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal){.+.+}-{0:0}:
       __lock_acquire+0x15a5/0x2d10
       lock_acquire+0x106/0x350
       percpu_down_read_internal+0x48/0x1d0
       ext4_evict_inode+0x426/0x10e0
       evict+0x61e/0xb10
       ext4_ext_migrate+0xe11/0x1130
       ext4_ioctl+0x2355/0x4b40
       __se_sys_ioctl+0xff/0x170
       do_syscall_64+0x15f/0xf80
       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.2.979/8376:
 #0: ffff88810cf36480 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210
 #1: ffff88811abed6d0 (&sb->s_type->i_mutex_key#11){++++}-{4:4}, at: ext4_ioctl+0x234d/0x4b40
 #2: ffff888116cd8cd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x308/0x1130

stack backtrace:
CPU: 0 UID: 0 PID: 8376 Comm: syz.2.979 Not tainted syzkaller #0 PREEMPT_{RT,(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+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x15a5/0x2d10
 lock_acquire+0x106/0x350
 percpu_down_read_internal+0x48/0x1d0
 ext4_evict_inode+0x426/0x10e0
 evict+0x61e/0xb10
 ext4_ext_migrate+0xe11/0x1130
 ext4_ioctl+0x2355/0x4b40
 __se_sys_ioctl+0xff/0x170
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa92ab1cdd9
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:00007fa928d6e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa92ad95fa0 RCX: 00007fa92ab1cdd9
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007fa92abb2d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa92ad96038 R14: 00007fa92ad95fa0 R15: 00007ffeef6df378
 </TASK>
