==================================================================
BUG: KCSAN: data-race in shmem_add_to_page_cache / shmem_getpage_gfp

read-write to 0xffff888106086b70 of 8 bytes by task 1733 on cpu 0:
 shmem_add_to_page_cache+0x802/0x8e0 mm/shmem.c:746
 shmem_getpage_gfp+0x7af/0x1750 mm/shmem.c:1951
 shmem_fault+0xd2/0x350 mm/shmem.c:2128
 __do_fault mm/memory.c:4173 [inline]
 do_read_fault mm/memory.c:4518 [inline]
 do_fault+0x500/0xb20 mm/memory.c:4647
 handle_pte_fault mm/memory.c:4911 [inline]
 __handle_mm_fault mm/memory.c:5053 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5151
 faultin_page mm/gup.c:990 [inline]
 __get_user_pages+0x34a/0xc40 mm/gup.c:1219
 populate_vma_page_range mm/gup.c:1576 [inline]
 __mm_populate+0x26e/0x3a0 mm/gup.c:1689
 mm_populate include/linux/mm.h:2663 [inline]
 __do_sys_remap_file_pages+0x39c/0x590 mm/mmap.c:2962
 __se_sys_remap_file_pages mm/mmap.c:2891 [inline]
 __x64_sys_remap_file_pages+0x63/0x70 mm/mmap.c:2891
 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+0x63/0xcd

read to 0xffff888106086b70 of 8 bytes by task 1732 on cpu 1:
 shmem_recalc_inode mm/shmem.c:363 [inline]
 shmem_getpage_gfp+0xd8b/0x1750 mm/shmem.c:1961
 shmem_fault+0xd2/0x350 mm/shmem.c:2128
 __do_fault mm/memory.c:4173 [inline]
 do_read_fault mm/memory.c:4518 [inline]
 do_fault+0x500/0xb20 mm/memory.c:4647
 handle_pte_fault mm/memory.c:4911 [inline]
 __handle_mm_fault mm/memory.c:5053 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5151
 do_user_addr_fault+0x4a1/0x980 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1488 [inline]
 exc_page_fault+0x60/0x160 arch/x86/mm/fault.c:1544
 asm_exc_page_fault+0x22/0x30
 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:2413 [inline]
 recvmsg_copy_msghdr+0x66/0x2d0 net/socket.c:2667
 ___sys_recvmsg net/socket.c:2739 [inline]
 do_recvmmsg+0x2ac/0x710 net/socket.c:2837
 __sys_recvmmsg net/socket.c:2916 [inline]
 __do_sys_recvmmsg net/socket.c:2939 [inline]
 __se_sys_recvmmsg net/socket.c:2932 [inline]
 __x64_sys_recvmmsg+0xde/0x160 net/socket.c:2932
 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+0x63/0xcd

value changed: 0x0000000000000063 -> 0x0000000000000064

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1732 Comm: syz-executor.3 Not tainted 6.0.0-rc4-syzkaller-00137-g506357871c18-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
==================================================================