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BUG: KCSAN: data-race in ksys_write / vfs_setpos

read to 0xffff88810836d768 of 8 bytes by task 28658 on cpu 1:
 vfs_setpos+0x88/0xf0 fs/read_write.c:61
 shmem_file_llseek+0xc0/0x120 mm/shmem.c:2737
 vfs_llseek fs/read_write.c:289 [inline]
 ksys_lseek fs/read_write.c:302 [inline]
 __do_sys_lseek fs/read_write.c:313 [inline]
 __se_sys_lseek fs/read_write.c:311 [inline]
 __x64_sys_lseek+0xe3/0x140 fs/read_write.c:311
 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

write to 0xffff88810836d768 of 8 bytes by task 28656 on cpu 0:
 ksys_write+0x11e/0x1a0 fs/read_write.c:639
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 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: 0x000000000000ff67 -> 0x000000000000ff68

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 28656 Comm: syz-executor.1 Not tainted 6.3.0-rc5-syzkaller-00032-g99ddf2254feb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
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