Re: [RFC][PATCH] proc: export more page flags in /proc/kpageflags

From: Andi Kleen
Date: Wed Apr 15 2009 - 09:55:24 EST


> That's pretty good separations. I guess it would be convenient to make the
> extra kernel flags available under CONFIG_DEBUG_KERNEL?

Yes.

BTW an alternative would be just someone implementing a suitable
command/macro in crash(1) and tell the kernel hackers to run that on
/proc/kcore. That would have the advantage to not require code.

> > > > > > - PG_compound
> >
> > I would combine these three into a pseudo "large page" flag.
>
> Very neat idea! Patch updated accordingly.
>
> However - one pity I observed:
>
> # ./page-areas 0x008000
> offset len KB
> 3088 4 16KB
>
> We can no longer tell if the above line means one 4-page hugepage, or two
> 2-page hugepages... Adding PG_COMPOUND_TAIL into the CONFIG_DEBUG_KERNEL block

There's only a single size (2 or 4MB), at worst two.

> >
> > PG_poison is also useful to export. But since it depends on my
> > patchkit I will pull a patch for that into the HWPOISON series.
>
> That's not a problem - since the PG_poison line is be protected by
> #ifdef CONFIG_MEMORY_FAILURE :-)

Good point. I added a patch to only add it to my pile,
but I can drop that again.

-Andi
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