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BUG: KCSAN: data-race in shmem_add_to_page_cache / shmem_getpage_gfp

read-write to 0xffff888127ad7920 of 8 bytes by task 16350 on cpu 0:
 shmem_add_to_page_cache+0x802/0x8f0 mm/shmem.c:745
 shmem_getpage_gfp+0x7af/0x1750 mm/shmem.c:1939
 shmem_fault+0xd2/0x350 mm/shmem.c:2116
 __do_fault mm/memory.c:4165 [inline]
 do_read_fault mm/memory.c:4511 [inline]
 do_fault+0x500/0xb20 mm/memory.c:4640
 handle_pte_fault mm/memory.c:4904 [inline]
 __handle_mm_fault mm/memory.c:5043 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5141
 do_user_addr_fault+0x4cd/0x940 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1484 [inline]
 exc_page_fault+0x60/0x160 arch/x86/mm/fault.c:1540
 asm_exc_page_fault+0x27/0x30
 copy_user_short_string+0xa/0x40
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 _copy_from_user+0x78/0xc0 lib/usercopy.c:16
 copy_from_user include/linux/uaccess.h:152 [inline]
 __copy_msghdr_from_user net/socket.c:2369 [inline]
 copy_msghdr_from_user net/socket.c:2421 [inline]
 recvmsg_copy_msghdr net/socket.c:2673 [inline]
 ___sys_recvmsg net/socket.c:2745 [inline]
 do_recvmmsg+0x281/0xa40 net/socket.c:2843
 __sys_recvmmsg net/socket.c:2922 [inline]
 __do_sys_recvmmsg net/socket.c:2945 [inline]
 __se_sys_recvmmsg net/socket.c:2938 [inline]
 __x64_sys_recvmmsg+0xde/0x160 net/socket.c:2938
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

read to 0xffff888127ad7920 of 8 bytes by task 16353 on cpu 1:
 shmem_recalc_inode mm/shmem.c:362 [inline]
 shmem_getpage_gfp+0xd8b/0x1750 mm/shmem.c:1949
 shmem_fault+0xd2/0x350 mm/shmem.c:2116
 __do_fault mm/memory.c:4165 [inline]
 do_read_fault mm/memory.c:4511 [inline]
 do_fault+0x500/0xb20 mm/memory.c:4640
 handle_pte_fault mm/memory.c:4904 [inline]
 __handle_mm_fault mm/memory.c:5043 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5141
 faultin_page mm/gup.c:953 [inline]
 __get_user_pages+0x34a/0xbf0 mm/gup.c:1174
 populate_vma_page_range mm/gup.c:1518 [inline]
 __mm_populate+0x26e/0x3a0 mm/gup.c:1631
 mm_populate include/linux/mm.h:2706 [inline]
 __do_sys_remap_file_pages+0x39c/0x590 mm/mmap.c:3008
 __se_sys_remap_file_pages mm/mmap.c:2937 [inline]
 __x64_sys_remap_file_pages+0x63/0x70 mm/mmap.c:2937
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

value changed: 0x0000000000000053 -> 0x0000000000000054

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16353 Comm: syz-executor.4 Not tainted 5.19.0-rc6-syzkaller-00026-g5a29232d870d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
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