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BUG: KCSAN: data-race in __anon_vma_prepare / wp_page_copy

write to 0xffff88810944abc8 of 8 bytes by task 7855 on cpu 1:
 __anon_vma_prepare+0x12f/0x2d0 mm/rmap.c:207
 anon_vma_prepare include/linux/rmap.h:152 [inline]
 wp_page_copy+0xb06/0x10c0 mm/memory.c:2887
 do_wp_page+0x5a8/0xba0 include/linux/spinlock_api_smp.h:152
 handle_pte_fault mm/memory.c:4385 [inline]
 __handle_mm_fault mm/memory.c:4502 [inline]
 handle_mm_fault+0xb31/0x1a70 mm/memory.c:4600
 do_user_addr_fault+0x60c/0xc00 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x94/0x230 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:577
 __put_user_nocheck_4+0x3/0x11
 ____sys_recvmsg+0x201/0x310 net/socket.c:2582
 ___sys_recvmsg net/socket.c:2611 [inline]
 do_recvmmsg+0x34c/0x9e0 net/socket.c:2705
 __sys_recvmmsg net/socket.c:2784 [inline]
 __do_sys_recvmmsg net/socket.c:2807 [inline]
 __se_sys_recvmmsg net/socket.c:2800 [inline]
 __x64_sys_recvmmsg+0xcf/0x150 net/socket.c:2800
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810944abc8 of 8 bytes by task 7831 on cpu 0:
 anon_vma_prepare include/linux/rmap.h:149 [inline]
 wp_page_copy+0x5f/0x10c0 mm/memory.c:2887
 do_wp_page+0x5a8/0xba0 include/linux/spinlock_api_smp.h:152
 handle_pte_fault mm/memory.c:4385 [inline]
 __handle_mm_fault mm/memory.c:4502 [inline]
 handle_mm_fault+0xb31/0x1a70 mm/memory.c:4600
 do_user_addr_fault+0x60c/0xc00 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x94/0x230 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:577
 __put_user_nocheck_4+0x3/0x11
 ____sys_recvmsg+0x201/0x310 net/socket.c:2582
 ___sys_recvmsg net/socket.c:2611 [inline]
 do_recvmmsg+0x34c/0x9e0 net/socket.c:2705
 __sys_recvmmsg net/socket.c:2784 [inline]
 __do_sys_recvmmsg net/socket.c:2807 [inline]
 __se_sys_recvmmsg net/socket.c:2800 [inline]
 __x64_sys_recvmmsg+0xcf/0x150 net/socket.c:2800
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7831 Comm: syz-executor.2 Tainted: G        W         5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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