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BUG: KCSAN: data-race in shmem_getattr / shmem_recalc_inode

read-write to 0xffff888119f67a30 of 8 bytes by task 4606 on cpu 1:
 shmem_recalc_inode+0x36/0x1c0 mm/shmem.c:442
 shmem_alloc_and_add_folio mm/shmem.c:1951 [inline]
 shmem_get_folio_gfp+0x7a3/0xd40 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_fallocate+0x57c/0x840 mm/shmem.c:3747
 vfs_fallocate+0x410/0x450 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x7a/0xd0 fs/open.c:365
 x64_sys_call+0x2b88/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888119f67a30 of 8 bytes by task 4609 on cpu 0:
 shmem_getattr+0x41/0x200 mm/shmem.c:1250
 vfs_getattr_nosec+0x143/0x1e0 fs/stat.c:210
 vfs_getattr fs/stat.c:259 [inline]
 vfs_statx_path fs/stat.c:296 [inline]
 vfs_statx+0x11a/0x380 fs/stat.c:353
 vfs_fstatat+0xe1/0x160 fs/stat.c:372
 __do_sys_newfstatat fs/stat.c:536 [inline]
 __se_sys_newfstatat+0x55/0x260 fs/stat.c:530
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:530
 x64_sys_call+0x2c22/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000000095a -> 0x0000000000000961

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4609 Comm: syz.4.384 Not tainted 6.15.0-rc6-syzkaller-00208-g3c21441eeffc #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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