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BUG: KCSAN: data-race in shmem_getattr / shmem_recalc_inode

read-write to 0xffff888121a742f8 of 8 bytes by task 9670 on cpu 1:
 shmem_recalc_inode+0x36/0x1b0 mm/shmem.c:437
 shmem_alloc_and_add_folio mm/shmem.c:1842 [inline]
 shmem_get_folio_gfp+0x7e4/0xd80 mm/shmem.c:2188
 shmem_get_folio mm/shmem.c:2293 [inline]
 shmem_write_begin+0xa0/0x1c0 mm/shmem.c:2898
 generic_perform_write+0x1b4/0x580 mm/filemap.c:4019
 shmem_file_write_iter+0xc8/0xf0 mm/shmem.c:3074
 __kernel_write_iter+0x24f/0x4e0 fs/read_write.c:523
 dump_emit_page fs/coredump.c:893 [inline]
 dump_user_range+0x3a7/0x550 fs/coredump.c:954
 elf_core_dump+0x1aeb/0x1c30 fs/binfmt_elf.c:2116
 do_coredump+0xfa7/0x1810 fs/coredump.c:767
 get_signal+0xdc1/0x1080 kernel/signal.c:2902
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888121a742f8 of 8 bytes by task 7936 on cpu 0:
 shmem_getattr+0x42/0x200 mm/shmem.c:1145
 vfs_getattr_nosec fs/stat.c:166 [inline]
 vfs_getattr+0x19b/0x1e0 fs/stat.c:207
 vfs_statx_path fs/stat.c:251 [inline]
 vfs_statx+0x134/0x2f0 fs/stat.c:315
 vfs_fstatat+0xec/0x110 fs/stat.c:341
 __do_sys_newfstatat fs/stat.c:505 [inline]
 __se_sys_newfstatat+0x58/0x260 fs/stat.c:499
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:499
 x64_sys_call+0x141f/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000000237f -> 0x0000000000002382

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7936 Comm: syz-executor Not tainted 6.11.0-rc3-syzkaller-00321-g810996a36309 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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