linux-kernel - [syzbot] [btrfs?] VFS: Busy inodes after unmount (use-after-free) (2)

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Message-ID: <682063e1.050a0220.f2294.002a.GAE@google.com>
Date: Sun, 11 May 2025 01:46:25 -0700
From: syzbot <syzbot+1134d3a5b062e9665a7a@...kaller.appspotmail.com>
To: clm@...com, dsterba@...e.com, josef@...icpanda.com, 
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [btrfs?] VFS: Busy inodes after unmount (use-after-free) (2)

Hello,

syzbot found the following issue on:

HEAD commit:    e0f4c8dd9d2d Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1481fb68580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=868079b7b8989c3c
dashboard link: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10edfa70580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=115a84d4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/463c704c2ee6/disk-e0f4c8dd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1bb99dd967d9/vmlinux-e0f4c8dd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/505fe552b9a8/Image-e0f4c8dd.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/3eef91541df5/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=176dfa70580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1134d3a5b062e9665a7a@...kaller.appspotmail.com

BTRFS info (device loop0): last unmount of filesystem c9fe44da-de57-406a-8241-57ec7d4412cf
VFS: Busy inodes after unmount of loop0 (btrfs)
------------[ cut here ]------------
kernel BUG at fs/super.c:652!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6484 Comm: syz-executor107 Not tainted 6.15.0-rc4-syzkaller-ge0f4c8dd9d2d #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : generic_shutdown_super+0x2b4/0x2b8 fs/super.c:650
lr : generic_shutdown_super+0x2b4/0x2b8 fs/super.c:650
sp : ffff8000a43f7ba0
x29: ffff8000a43f7ba0 x28: 00007dfe9b1ba808 x27: ffff80008f301de8
x26: ffffffffffffffff x25: dfff800000000000 x24: 1fffe00018b9bcf0
x23: ffff80008b2817e0 x22: dfff800000000000 x21: 0000000000000000
x20: ffff80008fa4d4c0 x19: ffff0000c5cde000 x18: 1fffe00036711a76
x17: ffff80008f2fe000 x16: ffff80008ada5d6c x15: 0000000000000001
x14: 1ffff0001487eee0 x13: 0000000000000000 x12: 0000000000000000
x11: ffff70001487eee1 x10: 0000000000ff0100 x9 : 9c3427ac6e3c7500
x8 : 9c3427ac6e3c7500 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a43f7538 x4 : ffff80008f3f4fa0 x3 : ffff800082faeee4
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 000000000000002f
Call trace:
 generic_shutdown_super+0x2b4/0x2b8 fs/super.c:650 (P)
 kill_anon_super+0x4c/0x7c fs/super.c:1237
 btrfs_kill_super+0x40/0x58 fs/btrfs/super.c:2099
 deactivate_locked_super+0xc4/0x12c fs/super.c:473
 deactivate_super+0xe0/0x100 fs/super.c:506
 cleanup_mnt+0x31c/0x3ac fs/namespace.c:1435
 __cleanup_mnt+0x20/0x30 fs/namespace.c:1442
 task_work_run+0x1dc/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 do_notify_resume+0x16c/0x1ec arch/arm64/kernel/entry-common.c:151
 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
 el0_svc+0xb0/0x150 arch/arm64/kernel/entry-common.c:745
 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Code: b0051160 91350000 9119a261 97cfbb64 (d4210000) 
---[ end trace 0000000000000000 ]---


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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