syzbot

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BUG: KCSAN: data-race in __anon_vma_prepare / __vmf_anon_prepare

write to 0xffff888104ef21c0 of 8 bytes by task 4203 on cpu 0:
 __anon_vma_prepare+0x172/0x2f0 mm/rmap.c:212
 __vmf_anon_prepare+0x91/0x100 mm/memory.c:3676
 hugetlb_no_page+0x1c5/0xf50 mm/hugetlb.c:5782
 hugetlb_fault+0x555/0xe00 mm/hugetlb.c:-1
 handle_mm_fault+0x1bea/0x3030 mm/memory.c:6581
 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
 rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:68
 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
 copy_from_user_iter lib/iov_iter.c:67 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:330 [inline]
 __copy_from_iter lib/iov_iter.c:261 [inline]
 _copy_from_iter+0x117/0xea0 lib/iov_iter.c:272
 copy_page_from_iter+0x178/0x2a0 lib/iov_iter.c:434
 process_vm_rw_pages mm/process_vm_access.c:43 [inline]
 process_vm_rw_single_vec mm/process_vm_access.c:118 [inline]
 process_vm_rw_core mm/process_vm_access.c:216 [inline]
 process_vm_rw+0x6ad/0x9c0 mm/process_vm_access.c:284
 __do_sys_process_vm_writev mm/process_vm_access.c:304 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:299 [inline]
 __x64_sys_process_vm_writev+0x78/0x90 mm/process_vm_access.c:299
 x64_sys_call+0x27ef/0x3000 arch/x86/include/generated/asm/syscalls_64.h:312
 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

read to 0xffff888104ef21c0 of 8 bytes by task 4209 on cpu 1:
 __vmf_anon_prepare+0x26/0x100 mm/memory.c:3670
 hugetlb_no_page+0x1c5/0xf50 mm/hugetlb.c:5782
 hugetlb_fault+0x555/0xe00 mm/hugetlb.c:-1
 handle_mm_fault+0x1bea/0x3030 mm/memory.c:6581
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1023/0x1ea0 mm/gup.c:1428
 populate_vma_page_range mm/gup.c:1860 [inline]
 __mm_populate+0x242/0x390 mm/gup.c:1963
 mm_populate include/linux/mm.h:3705 [inline]
 vm_mmap_pgoff+0x23b/0x2d0 mm/util.c:586
 ksys_mmap_pgoff+0x2cf/0x310 mm/mmap.c:604
 x64_sys_call+0x16bb/0x3000 arch/x86/include/generated/asm/syscalls_64.h:10
 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 -> 0xffff888104ff3d00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4209 Comm: syz.0.258 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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