kvm: emulating exchange as write
==================================================================
BUG: KCSAN: data-race in direct_page_fault / kvm_mmu_notifier_invalidate_range_end

write to 0xffffc90004162188 of 8 bytes by task 10532 on cpu 0:
 kvm_mmu_notifier_invalidate_range_end+0x39/0xa0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:453
 mn_hlist_invalidate_end mm/mmu_notifier.c:560 [inline]
 __mmu_notifier_invalidate_range_end+0x18e/0x210 mm/mmu_notifier.c:580
 mmu_notifier_invalidate_range_end include/linux/mmu_notifier.h:473 [inline]
 unmap_vmas+0x120/0x150 mm/memory.c:1342
 unmap_region+0x149/0x1e0 mm/mmap.c:2613
 __do_munmap+0x74d/0xbf0 mm/mmap.c:2833
 do_munmap mm/mmap.c:2844 [inline]
 mmap_region+0x59a/0x1330 mm/mmap.c:1715
 do_mmap+0x7ad/0xce0 mm/mmap.c:1545
 do_mmap_pgoff include/linux/mm.h:2596 [inline]
 vm_mmap_pgoff+0xed/0x170 mm/util.c:506
 ksys_mmap_pgoff+0x342/0x3a0 mm/mmap.c:1595
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffc90004162188 of 8 bytes by task 10512 on cpu 1:
 direct_page_fault+0x162/0x670 arch/x86/kvm/mmu/mmu.c:4121
 kvm_tdp_page_fault+0x92/0xa0 arch/x86/kvm/mmu/mmu.c:4208
 kvm_mmu_do_page_fault arch/x86/kvm/mmu.h:115 [inline]
 kvm_mmu_page_fault+0xca/0x410 arch/x86/kvm/mmu/mmu.c:5422
 handle_ept_violation+0x232/0x5c0 arch/x86/kvm/vmx/vmx.c:5314
 vmx_handle_exit+0x554/0xb40 arch/x86/kvm/vmx/vmx.c:6093
 vcpu_enter_guest+0x189c/0x23e0 arch/x86/kvm/x86.c:8593
 vcpu_run+0x26e/0x750 arch/x86/kvm/x86.c:8658
 kvm_arch_vcpu_ioctl_run+0x38d/0x690 arch/x86/kvm/x86.c:8879
 kvm_vcpu_ioctl+0x565/0x950 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3166
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl fs/ioctl.c:753 [inline]
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl+0xc9/0x130 fs/ioctl.c:760
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:760
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10512 Comm: syz-executor.2 Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================