Re: [syzbot] [v9fs?] WARNING in v9fs_begin_writeback

[syzbot <syzbot+0b74d367d6e80661d6df@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
VFS: Busy inodes after unmount (use-after-free)

VFS: Busy inodes after unmount of 9p (9p)
------------[ cut here ]------------
kernel BUG at fs/super.c:650!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5814 Comm: syz-executor Not tainted 6.11.0-rc1-syzkaller-00154-gc0ecd6388360-dirty #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:generic_shutdown_super+0x31b/0x3d0 fs/super.c:650
Code: 28 48 89 ea 48 c1 ea 03 80 3c 02 00 0f 85 aa 00 00 00 48 8b 55 00 48 8d b3 68 06 00 00 48 c7 c7 e0 5e 5d 8b e8 66 35 73 ff 90 <0f> 0b e8 4e e9 ef ff e9 2f fd ff ff e8 44 e9 ef ff e9 02 fd ff ff
RSP: 0018:ffffc900035a7d70 EFLAGS: 00010286
RAX: 0000000000000029 RBX: ffff888025fb4000 RCX: ffffffff816b0039
RDX: 0000000000000000 RSI: ffffffff816b9416 RDI: 0000000000000005
RBP: ffffffff8e438ce0 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: ffff888025fb49c0
R13: ffff888025fb4780 R14: 0000000000000000 R15: ffff88801a1d3540
FS:  0000555587d56500(0000) GS:ffff88806b000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555587d715c8 CR3: 000000002c722000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kill_anon_super+0x3a/0x60 fs/super.c:1237
 v9fs_kill_super+0x3d/0xa0 fs/9p/vfs_super.c:193
 deactivate_locked_super+0xbe/0x1a0 fs/super.c:473
 deactivate_super+0xde/0x100 fs/super.c:506
 cleanup_mnt+0x222/0x450 fs/namespace.c:1373
 task_work_run+0x14e/0x250 kernel/task_work.c:228
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5d0f3786e7
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:00007fff76269ff8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f5d0f3786e7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff7626a0b0
RBP: 00007fff7626a0b0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff7626b130
R13: 00007f5d0f3e4784 R14: 000000000001f21c R15: 00007fff7626b170
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:generic_shutdown_super+0x31b/0x3d0 fs/super.c:650
Code: 28 48 89 ea 48 c1 ea 03 80 3c 02 00 0f 85 aa 00 00 00 48 8b 55 00 48 8d b3 68 06 00 00 48 c7 c7 e0 5e 5d 8b e8 66 35 73 ff 90 <0f> 0b e8 4e e9 ef ff e9 2f fd ff ff e8 44 e9 ef ff e9 02 fd ff ff
RSP: 0018:ffffc900035a7d70 EFLAGS: 00010286
RAX: 0000000000000029 RBX: ffff888025fb4000 RCX: ffffffff816b0039
RDX: 0000000000000000 RSI: ffffffff816b9416 RDI: 0000000000000005
RBP: ffffffff8e438ce0 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: ffff888025fb49c0
R13: ffff888025fb4780 R14: 0000000000000000 R15: ffff88801a1d3540
FS:  0000555587d56500(0000) GS:ffff88806b000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555587d715c8 CR3: 000000002c722000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


Tested on:

commit:         c0ecd638 Merge tag 'pci-v6.11-fixes-1' of git://git.ke..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=157a16d5980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8da8b059e43c5370
dashboard link: https://syzkaller.appspot.com/bug?extid=0b74d367d6e80661d6df
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1347418d980000