Re: [PATCH 2/3] mm/page_table_check: Do WARN_ON instead of BUG_ON by default

[Pasha Tatashin]

On Sun, Sep 11, 2022 at 12:08 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Sun, Sep 11, 2022 at 09:59:22AM +0000, Pasha Tatashin wrote:
> > Currently, page_table_check when detects errors panics kernel. Instead,
> > print a warning, and panic only when specifically requested via kernel
> > parameter:
> >
> >       page_table_check=panic
>
> Why are the page table checks so special that they deserve their own
> command line parameter?  Why shouldn't this be controlled by the usual
> panic_on_warn option?

page_table_check can be used as a security feature preventing false
page sharing between address spaces. For example, at Google we want it
to keep enabled on production systems, yet we do not want to enable
panic_on_warn as it would cause panics for many other reasons which
are security unrelated.

Pasha