syzbot

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BUG: KCSAN: data-race in __anon_vma_prepare / handle_mm_fault

write to 0xffff888104dfcb80 of 8 bytes by task 4017 on cpu 0:
 __anon_vma_prepare+0x172/0x2f0 mm/rmap.c:212
 __vmf_anon_prepare mm/memory.c:3676 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_anonymous_page mm/memory.c:5221 [inline]
 do_pte_missing mm/memory.c:4402 [inline]
 handle_pte_fault mm/memory.c:6276 [inline]
 __handle_mm_fault mm/memory.c:6414 [inline]
 handle_mm_fault+0x2163/0x3030 mm/memory.c:6583
 do_user_addr_fault+0x62f/0x1050 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

read to 0xffff888104dfcb80 of 8 bytes by task 4019 on cpu 1:
 __vmf_anon_prepare mm/memory.c:3670 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_anonymous_page mm/memory.c:5221 [inline]
 do_pte_missing mm/memory.c:4402 [inline]
 handle_pte_fault mm/memory.c:6276 [inline]
 __handle_mm_fault mm/memory.c:6414 [inline]
 handle_mm_fault+0x10de/0x3030 mm/memory.c:6583
 do_user_addr_fault+0x3fd/0x1050 arch/x86/mm/fault.c:1385
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
 __put_user_4+0xd/0x20 arch/x86/lib/putuser.S:92
 __sys_socketpair+0xa6/0x420 net/socket.c:1797
 __do_sys_socketpair net/socket.c:1863 [inline]
 __se_sys_socketpair net/socket.c:1860 [inline]
 __x64_sys_socketpair+0x52/0x60 net/socket.c:1860
 x64_sys_call+0x2df3/0x3000 arch/x86/include/generated/asm/syscalls_64.h:54
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88810d7274e0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4019 Comm: syz.0.156 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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