syzbot

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BUG: KCSAN: data-race in __anon_vma_prepare / handle_mm_fault

write to 0xffff888114b0edc0 of 8 bytes by task 13510 on cpu 0:
 __anon_vma_prepare+0x172/0x2f0 mm/rmap.c:213
 __vmf_anon_prepare mm/memory.c:3506 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_anonymous_page mm/memory.c:5050 [inline]
 do_pte_missing mm/memory.c:4232 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0x1d58/0x2c20 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x102e/0x1fa0 mm/gup.c:1446
 populate_vma_page_range mm/gup.c:1880 [inline]
 __mm_populate+0x243/0x3a0 mm/gup.c:1983
 mm_populate include/linux/mm.h:3367 [inline]
 vm_mmap_pgoff+0x232/0x2e0 mm/util.c:585
 ksys_mmap_pgoff+0xc2/0x310 mm/mmap.c:604
 x64_sys_call+0x14a3/0x3000 arch/x86/include/generated/asm/syscalls_64.h:10
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888114b0edc0 of 8 bytes by task 13503 on cpu 1:
 __vmf_anon_prepare mm/memory.c:3500 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_anonymous_page mm/memory.c:5050 [inline]
 do_pte_missing mm/memory.c:4232 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0xe8e/0x2c20 mm/memory.c:6364
 do_user_addr_fault+0x3fe/0x1080 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
 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_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]
 _inline_copy_to_user include/linux/uaccess.h:197 [inline]
 _copy_to_user+0x7c/0xa0 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:225 [inline]
 rng_dev_read+0x3ef/0x740 drivers/char/hw_random/core.c:258
 do_loop_readv_writev fs/read_write.c:847 [inline]
 vfs_readv+0x3fb/0x690 fs/read_write.c:1020
 do_preadv fs/read_write.c:1132 [inline]
 __do_sys_preadv fs/read_write.c:1179 [inline]
 __se_sys_preadv fs/read_write.c:1174 [inline]
 __x64_sys_preadv+0xfd/0x1c0 fs/read_write.c:1174
 x64_sys_call+0x282e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:296
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff888125a7eb60

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13503 Comm: syz.4.3516 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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