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

[Yang Shi]

On 7/20/18 2:06 PM, Kirill A. Shutemov wrote:
> On Sat, Jul 21, 2018 at 02:13:50AM +0800, Yang Shi wrote:
> > By digging into the original review, it looks use_zero_page sysfs knob
> > was added to help ease-of-testing and give user a way to mitigate
> > refcounting overhead.
> >
> > It has been a few years since the knob was added at the first place, I
> > think we are confident that it is stable enough. And, since commit
> > 6fcb52a56ff60 ("thp: reduce usage of huge zero page's atomic counter"),
> > it looks refcounting overhead has been reduced significantly.
> >
> > Other than the above, the value of the knob is always 1 (enabled by
> > default), I'm supposed very few people turn it off by default.
> >
> > So, it sounds not worth to still keep this knob around.
> I don't think that having the knob around is huge maintenance burden.
> And since it helped to workaround a security bug relative recently I would
> rather keep it.

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.

>