KCSAN: data-race in kvm_arch_vcpu_load / kvm_vcpu_kick (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d4961772 Merge tag 'clk-fixes-for-linus' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160c935ed00000
kernel config: https://syzkaller.appspot.com/x/.config?x=766d02fe10aa7ea6
dashboard link: https://syzkaller.appspot.com/bug?extid=8c1a5261856a962bcc78
compiler: Debian clang version 11.0.1-2
CC: [b...@alien8.de h...@zytor.com jmat...@google.com jo...@8bytes.org k...@vger.kernel.org linux-...@vger.kernel.org mi...@redhat.com pbon...@redhat.com sea...@google.com tg...@linutronix.de vkuz...@redhat.com wanp...@tencent.com x...@kernel.org]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8c1a52...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in kvm_arch_vcpu_load / kvm_vcpu_kick

write to 0xffff8880274e8460 of 4 bytes by task 30718 on cpu 0:
kvm_arch_vcpu_load+0x3fc/0x550 arch/x86/kvm/x86.c:4018
kvm_sched_in+0x57/0x60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4864
__fire_sched_in_preempt_notifiers kernel/sched/core.c:3906 [inline]
fire_sched_in_preempt_notifiers kernel/sched/core.c:3912 [inline]
finish_task_switch+0x278/0x2a0 kernel/sched/core.c:4203
context_switch kernel/sched/core.c:4325 [inline]
__schedule+0x3c1/0x580 kernel/sched/core.c:5073
schedule+0x7f/0xb0 kernel/sched/core.c:5152
xfer_to_guest_mode_work kernel/entry/kvm.c:20 [inline]
xfer_to_guest_mode_handle_work+0x87/0x170 kernel/entry/kvm.c:50
vcpu_run+0x557/0x6a0 arch/x86/kvm/x86.c:9319
kvm_arch_vcpu_ioctl_run+0x476/0x860 arch/x86/kvm/x86.c:9525
kvm_vcpu_ioctl+0x562/0x8f0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3316
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
__x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8880274e8460 of 4 bytes by task 35 on cpu 1:
kvm_vcpu_kick+0x15/0x160 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2909
kvm_arch_async_page_present_queued+0x43/0x50 arch/x86/kvm/x86.c:11287
async_pf_execute+0x1d8/0x300 arch/x86/kvm/../../../virt/kvm/async_pf.c:79
process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
worker_thread+0x616/0xa70 kernel/workqueue.c:2421
kthread+0x20b/0x230 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 35 Comm: kworker/1:1 Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events async_pf_execute
==================================================================
usb 3-1: USB disconnect, device number 23
usb 3-1: new high-speed USB device number 24 using dummy_hcd
usb 3-1: Using ep0 maxpacket: 16
usb 3-1: config 1 interface 0 altsetting 0 has 1 endpoint descriptor, different from the interface descriptor's value: 0
usb 3-1: New USB device found, idVendor=0525, idProduct=a4a8, bcdDevice= 0.40
usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 3-1: Product: ࠐ
usb 3-1: Manufacturer: Х
usb 3-1: SerialNumber: syz
usb 3-1: USB disconnect, device number 24


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.