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BUG: KCSAN: data-race in shmem_add_to_page_cache / shmem_getpage_gfp

write to 0xffff888106e21800 of 8 bytes by task 3364 on cpu 0:
 shmem_add_to_page_cache+0x55d/0x670 mm/shmem.c:742
 shmem_getpage_gfp+0xaf1/0x12c0 mm/shmem.c:1936
 shmem_fault+0xd1/0x3c0 mm/shmem.c:2114
 __do_fault mm/memory.c:3849 [inline]
 do_read_fault mm/memory.c:4164 [inline]
 do_fault mm/memory.c:4293 [inline]
 handle_pte_fault mm/memory.c:4551 [inline]
 __handle_mm_fault mm/memory.c:4686 [inline]
 handle_mm_fault+0xba6/0x1590 mm/memory.c:4784
 faultin_page mm/gup.c:939 [inline]
 __get_user_pages+0x388/0xc80 mm/gup.c:1160
 populate_vma_page_range mm/gup.c:1492 [inline]
 __mm_populate+0x24d/0x370 mm/gup.c:1601
 mm_populate include/linux/mm.h:2734 [inline]
 vm_mmap_pgoff+0x160/0x1f0 mm/util.c:524
 ksys_mmap_pgoff+0xc2/0x320 mm/mmap.c:1623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888106e21800 of 8 bytes by task 3373 on cpu 1:
 shmem_recalc_inode mm/shmem.c:363 [inline]
 shmem_getpage_gfp+0xf23/0x12c0 mm/shmem.c:1946
 shmem_fault+0xd1/0x3c0 mm/shmem.c:2114
 __do_fault mm/memory.c:3849 [inline]
 do_read_fault mm/memory.c:4164 [inline]
 do_fault mm/memory.c:4293 [inline]
 handle_pte_fault mm/memory.c:4551 [inline]
 __handle_mm_fault mm/memory.c:4686 [inline]
 handle_mm_fault+0xba6/0x1590 mm/memory.c:4784
 faultin_page mm/gup.c:939 [inline]
 __get_user_pages+0x388/0xc80 mm/gup.c:1160
 populate_vma_page_range mm/gup.c:1492 [inline]
 __mm_populate+0x24d/0x370 mm/gup.c:1601
 mm_populate include/linux/mm.h:2734 [inline]
 __do_sys_mremap+0x2c6/0xde0 mm/mremap.c:1070
 __se_sys_mremap mm/mremap.c:889 [inline]
 __x64_sys_mremap+0x63/0x70 mm/mremap.c:889
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000031 -> 0x0000000000000032

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3373 Comm: syz-executor.3 Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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