linux-kernel - Re: [syzbot] [kernel?] WARNING in __vhost_task

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Message-ID: <68cb6475.050a0220.3c6139.0fab.GAE@google.com>
Date: Wed, 17 Sep 2025 18:46:29 -0700
From: syzbot <syzbot+a1a3cefd6148c781117c@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, luto@...nel.org, peterz@...radead.org, 
	syzkaller-bugs@...glegroups.com, tglx@...utronix.de
Subject: Re: [syzbot] [kernel?] WARNING in __vhost_task_wake

syzbot has found a reproducer for the following issue on:

HEAD commit:    ae2d20002576 Add linux-next specific files for 20250917
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11678f62580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d737cfaddae0058c
dashboard link: https://syzkaller.appspot.com/bug?extid=a1a3cefd6148c781117c
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1790ef62580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10242534580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/96197382e3c0/disk-ae2d2000.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/55a8a6ba3307/vmlinux-ae2d2000.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c1b4ed5d6e2c/bzImage-ae2d2000.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a1a3cefd6148c781117c@...kaller.appspotmail.com

------------[ cut here ]------------
WARNING: kernel/vhost_task.c:97 at __vhost_task_wake+0xbb/0xd0 kernel/vhost_task.c:97, CPU#0: syz.0.174/6507
Modules linked in:
CPU: 0 UID: 0 PID: 6507 Comm: syz.0.174 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__vhost_task_wake+0xbb/0xd0 kernel/vhost_task.c:97
Code: 38 00 74 08 48 89 df e8 93 81 95 00 48 8b 3b 5b 41 5e 41 5f e9 a6 45 01 00 e8 31 ef 30 00 90 0f 0b 90 eb 8b e8 26 ef 30 00 90 <0f> 0b 90 5b 41 5e 41 5f e9 18 c7 ff 09 cc 0f 1f 80 00 00 00 00 90
RSP: 0018:ffffc90003b7f680 EFLAGS: 00010293
RAX: ffffffff818f2d7a RBX: ffff888033c7c400 RCX: ffff88802bc85ac0
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: ffffc90003b7f750 R08: ffff888033c7c477 R09: 1ffff1100678f88e
R10: dffffc0000000000 R11: ffffed100678f88f R12: 1ffff9200076fed8
R13: dffffc0000000000 R14: 0000000000000002 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88812579c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9942aa0f98 CR3: 0000000027bfc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 vhost_worker_queue+0x194/0x260 drivers/vhost/vhost.c:253
 __vhost_worker_flush+0x134/0x1e0 drivers/vhost/vhost.c:290
 vhost_worker_flush drivers/vhost/vhost.c:303 [inline]
 vhost_dev_flush+0xb2/0x130 drivers/vhost/vhost.c:313
 vhost_vsock_flush drivers/vhost/vsock.c:698 [inline]
 vhost_vsock_dev_release+0x1fb/0x3f0 drivers/vhost/vsock.c:750
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:966
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
 get_signal+0x1285/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9941b8eba9
Code: Unable to access opcode bytes at 0x7f9941b8eb7f.
RSP: 002b:00007f9942aa10e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f9941dd5fa8 RCX: 00007f9941b8eba9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f9941dd5fa8
RBP: 00007f9941dd5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9941dd6038 R14: 00007ffd2989c130 R15: 00007ffd2989c218
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.