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BUG: KCSAN: data-race in do_sendfile / ksys_write

write to 0xffff8881033ecb68 of 8 bytes by task 27678 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

write to 0xffff8881033ecb68 of 8 bytes by task 27681 on cpu 1:
 do_sendfile+0x777/0x950
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 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: 0x0000000000000000 -> 0x00000000005f4000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27681 Comm: syz-executor.4 Not tainted 6.4.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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