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BUG: KCSAN: data-race in shmem_fallocate / shmem_fault

write to 0xffff888104b208a8 of 8 bytes by task 6199 on cpu 0:
 shmem_fallocate+0x221/0x840 mm/shmem.c:3678
 vfs_fallocate+0x3b6/0x400 fs/open.c:342
 madvise_remove mm/madvise.c:1049 [inline]
 madvise_vma_behavior+0x1920/0x1cf0 mm/madvise.c:1346
 madvise_walk_vmas mm/madvise.c:1669 [inline]
 madvise_do_behavior+0x5b7/0x970 mm/madvise.c:1885
 do_madvise+0x10e/0x190 mm/madvise.c:1978
 __do_sys_madvise mm/madvise.c:1987 [inline]
 __se_sys_madvise mm/madvise.c:1985 [inline]
 __x64_sys_madvise+0x64/0x80 mm/madvise.c:1985
 x64_sys_call+0x1f1a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:29
 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 0xffff888104b208a8 of 8 bytes by task 6195 on cpu 1:
 shmem_fault+0x90/0x250 mm/shmem.c:2727
 __do_fault+0xbc/0x200 mm/memory.c:5280
 do_shared_fault mm/memory.c:5762 [inline]
 do_fault mm/memory.c:5836 [inline]
 do_pte_missing mm/memory.c:4361 [inline]
 handle_pte_fault mm/memory.c:6177 [inline]
 __handle_mm_fault mm/memory.c:6318 [inline]
 handle_mm_fault+0xd69/0x2be0 mm/memory.c:6487
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x102a/0x1ed0 mm/gup.c:1428
 __get_user_pages_locked mm/gup.c:1692 [inline]
 faultin_page_range+0x107/0x4e0 mm/gup.c:1912
 madvise_populate mm/madvise.c:979 [inline]
 madvise_do_behavior+0x197/0x970 mm/madvise.c:1883
 do_madvise+0x10e/0x190 mm/madvise.c:1978
 __do_sys_madvise mm/madvise.c:1987 [inline]
 __se_sys_madvise mm/madvise.c:1985 [inline]
 __x64_sys_madvise+0x64/0x80 mm/madvise.c:1985
 x64_sys_call+0x1f1a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:29
 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 -> 0xffffc900059bbb58

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6195 Comm: syz.5.8383 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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