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BUG: KCSAN: data-race in shmem_add_to_page_cache / shmem_get_folio_gfp

read-write to 0xffff88812cba5450 of 8 bytes by task 12087 on cpu 1:
 shmem_add_to_page_cache+0x40a/0x510 mm/shmem.c:742
 shmem_get_folio_gfp+0x923/0x1200 mm/shmem.c:1978
 shmem_fault+0xe6/0x3f0 mm/shmem.c:2163
 __do_fault mm/memory.c:4191 [inline]
 do_read_fault mm/memory.c:4540 [inline]
 do_fault mm/memory.c:4663 [inline]
 do_pte_missing mm/memory.c:3664 [inline]
 handle_pte_fault mm/memory.c:4932 [inline]
 __handle_mm_fault mm/memory.c:5072 [inline]
 handle_mm_fault+0x1224/0x2c10 mm/memory.c:5226
 do_user_addr_fault arch/x86/mm/fault.c:1392 [inline]
 handle_page_fault arch/x86/mm/fault.c:1486 [inline]
 exc_page_fault+0x24d/0x650 arch/x86/mm/fault.c:1542
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
 rep_movs_alternative+0x30/0xb0 arch/x86/lib/copy_user_64.S:50
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:127 [inline]
 _copy_from_user+0x80/0xd0 lib/usercopy.c:23
 copy_from_user include/linux/uaccess.h:183 [inline]
 copy_msghdr_from_user+0x54/0x2a0 net/socket.c:2424
 recvmsg_copy_msghdr net/socket.c:2679 [inline]
 ___sys_recvmsg net/socket.c:2751 [inline]
 do_recvmmsg+0x290/0x720 net/socket.c:2849
 __sys_recvmmsg net/socket.c:2928 [inline]
 __do_sys_recvmmsg net/socket.c:2951 [inline]
 __se_sys_recvmmsg net/socket.c:2944 [inline]
 __x64_sys_recvmmsg+0xe2/0x160 net/socket.c:2944
 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 0xffff88812cba5450 of 8 bytes by task 12078 on cpu 0:
 shmem_recalc_inode mm/shmem.c:360 [inline]
 shmem_get_folio_gfp+0xe1e/0x1200 mm/shmem.c:1988
 shmem_fault+0xe6/0x3f0 mm/shmem.c:2163
 __do_fault mm/memory.c:4191 [inline]
 do_shared_fault mm/memory.c:4595 [inline]
 do_fault mm/memory.c:4667 [inline]
 do_pte_missing mm/memory.c:3664 [inline]
 handle_pte_fault mm/memory.c:4932 [inline]
 __handle_mm_fault mm/memory.c:5072 [inline]
 handle_mm_fault+0x131b/0x2c10 mm/memory.c:5226
 do_user_addr_fault arch/x86/mm/fault.c:1392 [inline]
 handle_page_fault arch/x86/mm/fault.c:1486 [inline]
 exc_page_fault+0x24d/0x650 arch/x86/mm/fault.c:1542
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

value changed: 0x000000000000000b -> 0x000000000000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12078 Comm: syz-executor.4 Not tainted 6.4.0-syzkaller-10096-gdfab92f27c60 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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