[moderation] [fs?] VFS: Busy inodes after unmount (use-after-free) (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d31f578f323 Add linux-next specific files for 20251128
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1335bc2c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6336d8e94a7c517d
dashboard link: https://syzkaller.appspot.com/bug?extid=7970e097e49168b7d0ca
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b49d8ad90de/disk-7d31f578.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dbe2d4988ca7/vmlinux-7d31f578.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0448ab2411/bzImage-7d31f578.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7970e0...@syzkaller.appspotmail.com

tblock:ffffc900027192f0: 00000000 00000000 00000000 00000000
tblock:ffffc90002719300: 8ba53820 ffffffff 00000300 00000000
tblock:ffffc90002719310: 02719310 ffffc900 02719310 ffffc900
tblock:ffffc90002719320: 65fa1680 ffff8880 00000000 00000000
VFS: Busy inodes after unmount of loop7 (jfs)
------------[ cut here ]------------
kernel BUG at fs/super.c:653!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 7887 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:generic_shutdown_super+0x2bc/0x2c0 fs/super.c:651
Code: 03 42 80 3c 28 00 74 08 4c 89 f7 e8 2e f2 ed ff 49 8b 16 48 81 c3 68 06 00 00 48 c7 c7 60 b4 79 8b 48 89 de e8 65 9a ed fe 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
RSP: 0018:ffffc90003ddfce0 EFLAGS: 00010246
RAX: 000000000000002d RBX: ffff88807e8e2668 RCX: d6c2b8b36f5a7200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 1ffff1100fd1c4f0 R08: ffffc90003ddfa07 R09: 1ffff920007bbf40
R10: dffffc0000000000 R11: fffff520007bbf41 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8e383e80 R15: ffff88807e8e2780
FS: 0000555589251500(0000) GS:ffff888125e4f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f999fc7d000 CR3: 000000002e7aa000 CR4: 00000000003526f0
Call Trace:
<TASK>
kill_block_super+0x44/0x90 fs/super.c:1722
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1328
task_work_run+0x1d4/0x260 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1263190a77
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffc2e9f4868 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000064 RCX: 00007f1263190a77
RDX: 0000000000000200 RSI: 0000000000000009 RDI: 00007ffc2e9f5a10
RBP: 00007f1263213d7d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc2e9f5a10
R13: 00007f1263213d7d R14: 00005555892514a8 R15: 00007ffc2e9f6ae0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:generic_shutdown_super+0x2bc/0x2c0 fs/super.c:651
Code: 03 42 80 3c 28 00 74 08 4c 89 f7 e8 2e f2 ed ff 49 8b 16 48 81 c3 68 06 00 00 48 c7 c7 60 b4 79 8b 48 89 de e8 65 9a ed fe 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
RSP: 0018:ffffc90003ddfce0 EFLAGS: 00010246
RAX: 000000000000002d RBX: ffff88807e8e2668 RCX: d6c2b8b36f5a7200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 1ffff1100fd1c4f0 R08: ffffc90003ddfa07 R09: 1ffff920007bbf40
R10: dffffc0000000000 R11: fffff520007bbf41 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8e383e80 R15: ffff88807e8e2780
FS: 0000555589251500(0000) GS:ffff888125f4f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005612f5398000 CR3: 000000002e7aa000 CR4: 00000000003526f0


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