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BUG: KCSAN: data-race in do_sendfile / do_sendfile

write to 0xffff888136bfa140 of 8 bytes by task 28965 on cpu 0:
 do_sendfile+0x76f/0x9a0 fs/read_write.c:1269
 __do_sys_sendfile64 fs/read_write.c:1316 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0xbd/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 0xffff888136bfa140 of 8 bytes by task 28964 on cpu 1:
 do_sendfile+0x76f/0x9a0 fs/read_write.c:1269
 __do_sys_sendfile64 fs/read_write.c:1316 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0xbd/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: 0x00000000000000bf -> 0x0000000000000539

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 28964 Comm: syz-executor.2 Not tainted 6.4.0-syzkaller-11478-gd528014517f2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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