Re: Do we need to unrevert "fs: do not prefault sys_write() user buffer pages"?
From: David Howells <dhowells@redhat.com>
Date: 2021-06-22 17:55:45
Also in:
linux-fsdevel, linux-mm, lkml
Linus Torvalds [off-list ref] wrote:
End result: doing the fault_in_readable "unnecessarily" at the beginning is likely the better optimization. It's basically free when it's not necessary, and it avoids an extra fault (and extra lock/unlock and retry) when it does end up faulting pages in.
It may also cause the read in to happen in the background whilst write_begin is being done. David