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BUG: KCSAN: data-race in shmem_add_to_page_cache / shmem_get_folio_gfp

read-write to 0xffff8881052b6570 of 8 bytes by task 15082 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+0xe5/0x3d0 mm/shmem.c:2163
 __do_fault mm/memory.c:4176 [inline]
 do_shared_fault mm/memory.c:4585 [inline]
 do_fault mm/memory.c:4663 [inline]
 do_pte_missing mm/memory.c:3647 [inline]
 handle_pte_fault mm/memory.c:4947 [inline]
 __handle_mm_fault mm/memory.c:5089 [inline]
 handle_mm_fault+0x1495/0x2c60 mm/memory.c:5243
 do_user_addr_fault arch/x86/mm/fault.c:1440 [inline]
 handle_page_fault arch/x86/mm/fault.c:1534 [inline]
 exc_page_fault+0x67e/0x780 arch/x86/mm/fault.c:1590
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
 rep_movs_alternative+0x4a/0xb0 arch/x86/lib/copy_user_64.S:65
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline]
 copyout lib/iov_iter.c:168 [inline]
 _copy_to_iter+0x13c/0x910 lib/iov_iter.c:316
 copy_to_iter include/linux/uio.h:194 [inline]
 get_random_bytes_user+0x112/0x260 drivers/char/random.c:451
 __do_sys_getrandom drivers/char/random.c:1391 [inline]
 __se_sys_getrandom drivers/char/random.c:1364 [inline]
 __x64_sys_getrandom+0xcd/0x1a0 drivers/char/random.c:1364
 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 0xffff8881052b6570 of 8 bytes by task 15083 on cpu 0:
 shmem_recalc_inode mm/shmem.c:360 [inline]
 shmem_get_folio_gfp+0xe1e/0x1200 mm/shmem.c:1988
 shmem_fault+0xe5/0x3d0 mm/shmem.c:2163
 __do_fault mm/memory.c:4176 [inline]
 do_read_fault mm/memory.c:4530 [inline]
 do_fault mm/memory.c:4659 [inline]
 do_pte_missing mm/memory.c:3647 [inline]
 handle_pte_fault mm/memory.c:4947 [inline]
 __handle_mm_fault mm/memory.c:5089 [inline]
 handle_mm_fault+0x12f4/0x2c60 mm/memory.c:5243
 faultin_page mm/gup.c:969 [inline]
 __get_user_pages+0x363/0xc30 mm/gup.c:1191
 populate_vma_page_range mm/gup.c:1587 [inline]
 __mm_populate+0x23d/0x370 mm/gup.c:1696
 mm_populate include/linux/mm.h:3176 [inline]
 vm_mmap_pgoff+0x1a3/0x240 mm/util.c:548
 ksys_mmap_pgoff+0xc5/0x330 mm/mmap.c:1440
 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

value changed: 0x0000000000000047 -> 0x0000000000000048

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15083 Comm: syz-executor.5 Not tainted 6.4.0-syzkaller-01761-g6aeadf7896bf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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