WARNING: ODEBUG bug in ext4_fill_super (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    0d52778b Add linux-next specific files for 20201218
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16190613500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5c81cc44aa25b5b3
dashboard link: https://syzkaller.appspot.com/bug?extid=3002ac6b4fd242a64228
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=128f5123500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14f9f30f500000

The issue was bisected to:

commit e810c942a325cf749e859d7aa3a43dc219cea299
Author: Jan Kara <jack@xxxxxxx>
Date:   Wed Dec 16 10:18:40 2020 +0000

    ext4: save error info to sb through journal if available

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12d9df07500000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=11d9df07500000
console output: https://syzkaller.appspot.com/x/log.txt?x=16d9df07500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3002ac6b4fd242a64228@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: e810c942a325 ("ext4: save error info to sb through journal if available")

EXT4-fs error (device loop3): ext4_fill_super:4943: inode #2: comm syz-executor723: iget: root inode unallocated
EXT4-fs (loop3): get root inode failed
EXT4-fs (loop3): mount failed
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: work_struct hint: flush_stashed_error_work+0x0/0x2a0 fs/ext4/ext4.h:2040
WARNING: CPU: 0 PID: 13670 at lib/debugobjects.c:505 debug_print_object+0x16e/0x250 lib/debugobjects.c:505
Modules linked in:
CPU: 0 PID: 13670 Comm: syz-executor723 Not tainted 5.10.0-next-20201218-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:505
Code: ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 00 00 00 48 8b 14 dd 20 af bf 89 4c 89 ee 48 c7 c7 20 a3 bf 89 e8 30 78 05 05 <0f> 0b 83 05 55 8a b9 09 01 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e c3
RSP: 0018:ffffc90001d0f9b8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: ffff888024b63600 RSI: ffffffff815b95f5 RDI: fffff520003a1f29
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815b7a4b R11: 0000000000000000 R12: ffffffff896ae040
R13: ffffffff89bfa920 R14: ffffffff814911f0 R15: dffffc0000000000
FS:  000000000163a940(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000043fb60 CR3: 000000001226b000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __debug_check_no_obj_freed lib/debugobjects.c:987 [inline]
 debug_check_no_obj_freed+0x309/0x430 lib/debugobjects.c:1018
 slab_free_hook mm/slub.c:1540 [inline]
 slab_free_freelist_hook+0x12b/0x1d0 mm/slub.c:1586
 slab_free mm/slub.c:3157 [inline]
 kfree+0xdb/0x3c0 mm/slub.c:4156
 ext4_fill_super+0x86c/0xdf40 fs/ext4/super.c:5174
 mount_bdev+0x34d/0x410 fs/super.c:1366
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1496
 do_new_mount fs/namespace.c:2896 [inline]
 path_mount+0x12ae/0x1e70 fs/namespace.c:3227
 do_mount fs/namespace.c:3240 [inline]
 __do_sys_mount fs/namespace.c:3448 [inline]
 __se_sys_mount fs/namespace.c:3425 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3425
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x44873a
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 cd a2 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 aa a2 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007fff16496da8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff16496e00 RCX: 000000000044873a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fff16496dc0
RBP: 00007fff16496dc0 R08: 00007fff16496e00 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000006
R13: 0000000000000005 R14: 0000000000000004 R15: 0000000000000004


---
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