Re: [PATCH] mm: thp: remove use_zero_page sysfs knob

[Yang Shi]

On 7/23/18 1:31 PM, David Rientjes wrote:
> On Fri, 20 Jul 2018, Yang Shi wrote:
>
> > I agree to keep it for a while to let that security bug cool down, however, if
> > there is no user anymore, it sounds pointless to still keep a dead knob.
> It's not a dead knob.  We use it, and for reasons other than
> CVE-2017-1000405.  To mitigate the cost of constantly compacting memory to
> allocate it after it has been freed due to memry pressure, we can either
> continue to disable it, allow it to be persistently available, or use a
> new value for use_zero_page to specify it should be persistently
> available.

My understanding is the cost of memory compaction is *not* unique for 
huge zero page, right? It is expected when memory pressure is met, even 
though huge zero page is disabled.