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SubjectRe: [PATCH/RFC] mm/debug_pagealloc: enable it by default
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On 01/25/2016 08:38 PM, Dave Jones wrote:
> Content preview: On Mon, Jan 25, 2016 at 02:22:10PM -0500, Dave Jones wrote:
> > > A default mode would be ok for me as it makes things obvious. Will send
> > > a patch. > > The messaging around changing a default like this was really
> poor. > When we do behaviour changes like this, we typically rename the CONFIG
> option > to make it obvious that things aren't as they used to be. [...]
>
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> On Mon, Jan 25, 2016 at 02:22:10PM -0500, Dave Jones wrote:
>
> > > A default mode would be ok for me as it makes things obvious. Will send
> > > a patch.
> >
> > The messaging around changing a default like this was really poor.
> > When we do behaviour changes like this, we typically rename the CONFIG option
> > to make it obvious that things aren't as they used to be.
>
> Looking at this closer, shouldn't the original diff to make this runtime
> have also changed the x86 implementation details in arch/x86/mm/pageattr.c ?
> Even when we don't boot with the enable flag, we're doing the "split 2M page into 4Ks"
> thing. It looks like a s/debug_pagealloc/debug_pagealloc_enabled()/ might
> do the right thing maybe ?

I have some patches ready, that fix the identity mapping for s390 and x86. sparc
is hard to do as it allocates the TSB very early. Will send around what I have soon.

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