Messages in this thread | | | Subject | Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache | From | Juerg Haefliger <> | Date | Wed, 14 Sep 2016 16:40:49 +0200 |
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Hi Dave,
On 09/14/2016 04:33 PM, Dave Hansen wrote: > On 09/14/2016 12:19 AM, Juerg Haefliger wrote: >> Allocating a page to userspace that was previously allocated to the >> kernel requires an expensive TLB shootdown. To minimize this, we only >> put non-kernel pages into the hot cache to favor their allocation. > > Hi, I had some questions about this the last time you posted it. Maybe > you want to address them now.
I did reply: https://lkml.org/lkml/2016/9/5/249
...Juerg
> -- > > But kernel allocations do allocate from these pools, right? Does this > just mean that kernel allocations usually have to pay the penalty to > convert a page? > > So, what's the logic here? You're assuming that order-0 kernel > allocations are more rare than allocations for userspace? >
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