linux-kernel - Re: [PATCH] mm: thp: remove use_zero

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Date:   Mon, 23 Jul 2018 13:31:08 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
cc:     "Kirill A. Shutemov" <kirill@...temov.name>, hughd@...gle.com,
        aaron.lu@...el.com, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: thp: remove use_zero_page sysfs knob

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.