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.
