syzbot

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BUG: KCSAN: data-race in cgroup_migrate_add_task / vcpu_enter_guest

read to 0xffff8880ab523064 of 4 bytes by task 9574 on cpu 1:
 cgroup_migrate_add_task+0x3d/0x440 kernel/cgroup/cgroup.c:2298
 cgroup_update_dfl_csses+0x2d3/0x350 kernel/cgroup/cgroup.c:2909
 cgroup_apply_control kernel/cgroup/cgroup.c:3153 [inline]
 cgroup_apply_control+0x47/0x60 kernel/cgroup/cgroup.c:3138
 cgroup_subtree_control_write+0x598/0x760 kernel/cgroup/cgroup.c:3302
 cgroup_file_write+0x119/0x320 kernel/cgroup/cgroup.c:3699
 kernfs_fop_write+0x1bd/0x300 fs/kernfs/file.c:315
 __vfs_write+0x67/0xc0 fs/read_write.c:494
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880ab523064 of 4 bytes by task 9569 on cpu 0:
 guest_enter_irqoff include/linux/context_tracking.h:145 [inline]
 vcpu_enter_guest+0x7b3/0x3860 arch/x86/kvm/x86.c:8199
 vcpu_run arch/x86/kvm/x86.c:8354 [inline]
 kvm_arch_vcpu_ioctl_run+0x2a8/0xdf0 arch/x86/kvm/x86.c:8561
 kvm_vcpu_ioctl+0x758/0xa30 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2847
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x84f/0xcf0 fs/ioctl.c:732
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:754
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9569 Comm: syz-executor.1 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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