[Bug libgcc/91053] __builtin___clear_cache can fail

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91053

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So was reading the code.  The only time a fault will happen when a page is not
mapped in.  This happens if the page was paged out (this is why it happens
under heavily pressure).  This is not about being privileged at all.