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BUG: KCSAN: data-race in do_sendfile / do_sendfile

write to 0xffff888137e75a68 of 8 bytes by task 2644 on cpu 0:
 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

write to 0xffff888137e75a68 of 8 bytes by task 2639 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 -> 0x0000000000080000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2639 Comm: syz-executor.2 Not tainted 6.3.0-syzkaller-10125-g35fab9271b7e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
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