Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache

2016-09-20 Thread Juerg Haefliger
On 09/14/2016 04:48 PM, Dave Hansen wrote: >> On 09/02/2016 10:39 PM, Dave Hansen wrote: >>> On 09/02/2016 04:39 AM, Juerg Haefliger wrote: >>> Does this >>> just mean that kernel allocations usually have to pay the penalty to >>> convert a page? >> >> Only pages that are allocated for userspace (g

Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache

2016-09-14 Thread Dave Hansen
> On 09/02/2016 10:39 PM, Dave Hansen wrote: >> On 09/02/2016 04:39 AM, Juerg Haefliger wrote: >> Does this >> just mean that kernel allocations usually have to pay the penalty to >> convert a page? > > Only pages that are allocated for userspace (gfp & GFP_HIGHUSER == > GFP_HIGHUSER) which were

Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache

2016-09-14 Thread Juerg Haefliger
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 t

Re: [kernel-hardening] [RFC PATCH v2 2/3] xpfo: Only put previous userspace pages into the hot cache

2016-09-14 Thread Dave Hansen
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