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BUG: KCSAN: data-race in shmem_fallocate / shmem_fault

write to 0xffff8881678eade0 of 8 bytes by task 9398 on cpu 0:
 shmem_fallocate+0x33e/0x870 mm/shmem.c:3067
 vfs_fallocate+0x378/0x3e0 fs/open.c:324
 madvise_remove mm/madvise.c:1011 [inline]
 madvise_vma_behavior mm/madvise.c:1035 [inline]
 madvise_walk_vmas mm/madvise.c:1270 [inline]
 do_madvise+0x7a9/0x2970 mm/madvise.c:1450
 __do_sys_madvise mm/madvise.c:1463 [inline]
 __se_sys_madvise mm/madvise.c:1461 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1461
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881678eade0 of 8 bytes by task 9399 on cpu 1:
 shmem_fault+0x9f/0x430 mm/shmem.c:2185
 __do_fault mm/memory.c:4204 [inline]
 do_read_fault mm/memory.c:4568 [inline]
 do_fault mm/memory.c:4705 [inline]
 do_pte_missing mm/memory.c:3669 [inline]
 handle_pte_fault mm/memory.c:4978 [inline]
 __handle_mm_fault mm/memory.c:5119 [inline]
 handle_mm_fault+0x15e2/0x2cc0 mm/memory.c:5284
 faultin_page mm/gup.c:956 [inline]
 __get_user_pages+0x402/0xe40 mm/gup.c:1239
 populate_vma_page_range mm/gup.c:1666 [inline]
 __mm_populate+0x216/0x330 mm/gup.c:1775
 mm_populate include/linux/mm.h:3305 [inline]
 vm_mmap_pgoff+0x1a7/0x240 mm/util.c:551
 ksys_mmap_pgoff+0xc5/0x330 mm/mmap.c:1400
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffffc9000109bcd8 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9399 Comm: syz-executor.5 Not tainted 6.6.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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