Re: [PATCH 01/11] x86/mm/pat: Don't free PGD entries on memory unmap

From: Andy Lutomirski
Date: Tue Sep 22 2015 - 14:03:50 EST


On Tue, Sep 22, 2015 at 10:41 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Sep 21, 2015 at 11:23 PM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>>
>> This complicates PGD management, so don't do this. We can keep the
>> PGD mapped and the PUD table all clear - it's only a single 4K page
>> per 512 GB of memory mapped.
>
> I'm ok with this just from a "it removes code" standpoint. That said,
> some of the other patches here make me go "hmm". I'll answer them
> separately.
>

If we want to get rid of vmalloc faults, then this patch makes it much
more obvious that it can be done without hurting performance.

> Linus



--
Andy Lutomirski
AMA Capital Management, LLC
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