[moderation] [mm?] KCSAN: data-race in __anon_vma_prepare / handle_mm_fault (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fc02acf6ac0c Merge tag 'platform-drivers-x86-v7.2-4' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=144f8aea580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=abd0c607e27faa68a33b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [ak...@linux-foundation.org da...@kernel.org ha...@kernel.org ja...@google.com lance...@linux.dev li...@infradead.org linux-...@vger.kernel.org linu...@kvack.org l...@kernel.org ri...@surriel.com vba...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5213866cd074/disk-fc02acf6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e75f2151b444/vmlinux-fc02acf6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea07b016de6c/bzImage-fc02acf6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+abd0c6...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __anon_vma_prepare / handle_mm_fault

write to 0xffff88811c31b700 of 8 bytes by task 17788 on cpu 0:
__anon_vma_prepare+0x172/0x2f0 mm/rmap.c:212
__vmf_anon_prepare mm/memory.c:3829 [inline]
vmf_anon_prepare mm/internal.h:494 [inline]
do_anonymous_page mm/memory.c:5338 [inline]
do_pte_missing mm/memory.c:4564 [inline]
handle_pte_fault mm/memory.c:6379 [inline]
__handle_mm_fault mm/memory.c:6517 [inline]
handle_mm_fault+0x2405/0x2da0 mm/memory.c:6686
do_user_addr_fault+0x402/0x1060 arch/x86/mm/fault.c:1394
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
__put_user_4+0xd/0x30 arch/x86/lib/putuser.S:92
__sys_socketpair+0xa6/0x430 net/socket.c:1843
__do_sys_socketpair net/socket.c:1909 [inline]
__se_sys_socketpair net/socket.c:1906 [inline]
__x64_sys_socketpair+0x52/0x60 net/socket.c:1906
x64_sys_call+0x2de5/0x3020 arch/x86/include/generated/asm/syscalls_64.h:54
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811c31b700 of 8 bytes by task 17787 on cpu 1:
__vmf_anon_prepare mm/memory.c:3823 [inline]
vmf_anon_prepare mm/internal.h:494 [inline]
do_anonymous_page mm/memory.c:5338 [inline]
do_pte_missing mm/memory.c:4564 [inline]
handle_pte_fault mm/memory.c:6379 [inline]
__handle_mm_fault mm/memory.c:6517 [inline]
handle_mm_fault+0xfdf/0x2da0 mm/memory.c:6686
do_user_addr_fault+0x634/0x1060 arch/x86/mm/fault.c:1343
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

value changed: 0x0000000000000000 -> 0xffff888104f08300

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 17787 Comm: syz.3.13285 Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================


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