Re: [BUG] copy_file_range with sysfs file as input

[Greg KH]

On Mon, Jan 25, 2021 at 03:54:31PM +0800, Nicolas Boichat wrote:
> Hi copy_file_range experts,
> 
> We hit this interesting issue when upgrading Go compiler from 1.13 to
> 1.15 [1]. Basically we use Go's `io.Copy` to copy the content of
> `/sys/kernel/debug/tracing/trace` to a temporary file.

Nit, the above file is NOT a sysfs file.  Odds are it is either a
debugfs, or a tracefs file, please check your mounts to determine which
it is, as that matters a lot on the kernel backend side for trying to
figure out what is going on here :)

thanks,

greg k-h