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BUG: KCSAN: data-race in __anon_vma_prepare / wp_page_copy

write to 0xffff88812f5d9b08 of 8 bytes by task 28604 on cpu 1:
 __anon_vma_prepare+0x12f/0x2d0 mm/rmap.c:207
 anon_vma_prepare include/linux/rmap.h:153 [inline]
 wp_page_copy+0xb0e/0x10c0 mm/memory.c:2897
 do_wp_page+0x5a8/0xba0 include/linux/spinlock_api_smp.h:152
 handle_pte_fault mm/memory.c:4438 [inline]
 __handle_mm_fault mm/memory.c:4555 [inline]
 handle_mm_fault+0xb28/0x1a60 mm/memory.c:4653
 do_user_addr_fault+0x609/0xc00 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568

read to 0xffff88812f5d9b08 of 8 bytes by task 28628 on cpu 0:
 anon_vma_prepare include/linux/rmap.h:150 [inline]
 wp_page_copy+0x5f/0x10c0 mm/memory.c:2897
 do_wp_page+0x5a8/0xba0 include/linux/spinlock_api_smp.h:152
 handle_pte_fault mm/memory.c:4438 [inline]
 __handle_mm_fault mm/memory.c:4555 [inline]
 handle_mm_fault+0xb28/0x1a60 mm/memory.c:4653
 do_user_addr_fault+0x609/0xc00 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
 __put_user_nocheck_4+0x3/0x11
 __sys_socketpair+0xb2/0x800 net/socket.c:1581
 __do_sys_socketpair net/socket.c:1647 [inline]
 __se_sys_socketpair net/socket.c:1644 [inline]
 __x64_sys_socketpair+0x4e/0x60 net/socket.c:1644
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000000 -> 0xffff888104f6d280

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 28628 Comm: syz-executor.4 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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