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BUG: KCSAN: data-race in shmem_fallocate / shmem_fault

write to 0xffff888142195480 of 8 bytes by task 5822 on cpu 0:
 shmem_fallocate+0x32f/0x860 mm/shmem.c:3080
 vfs_fallocate+0x378/0x3e0 fs/open.c:324
 madvise_remove mm/madvise.c:990 [inline]
 madvise_vma_behavior mm/madvise.c:1014 [inline]
 madvise_walk_vmas mm/madvise.c:1249 [inline]
 do_madvise+0x741/0x26f0 mm/madvise.c:1429
 __do_sys_madvise mm/madvise.c:1442 [inline]
 __se_sys_madvise mm/madvise.c:1440 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1440
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888142195480 of 8 bytes by task 5821 on cpu 1:
 shmem_fault+0x9d/0x250 mm/shmem.c:2206
 __do_fault mm/memory.c:4265 [inline]
 do_read_fault mm/memory.c:4628 [inline]
 do_fault mm/memory.c:4762 [inline]
 do_pte_missing mm/memory.c:3730 [inline]
 handle_pte_fault mm/memory.c:5038 [inline]
 __handle_mm_fault mm/memory.c:5179 [inline]
 handle_mm_fault+0x13bd/0x2dd0 mm/memory.c:5344
 faultin_page mm/gup.c:956 [inline]
 __get_user_pages+0x402/0xe40 mm/gup.c:1239
 populate_vma_page_range mm/gup.c:1677 [inline]
 __mm_populate+0x216/0x330 mm/gup.c:1786
 mm_populate include/linux/mm.h:3379 [inline]
 vm_mmap_pgoff+0x1a7/0x240 mm/util.c:551
 ksys_mmap_pgoff+0xc5/0x330 mm/mmap.c:1425
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0xffffc9000d653cd0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5821 Comm: syz-executor.2 Not tainted 6.7.0-rc1-syzkaller-00012-g9bacdd8996c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
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