Date: Fri, 23 Oct 2020 10:23:07 +0200 From: David Hildenbrand <david@...hat.com> To: Michal Hocko <mhocko@...e.com> Cc: Mike Kravetz <mike.kravetz@...cle.com>, "Guilherme G. Piccoli" <gpiccoli@...onical.com>, linux-mm@...ck.org, kernel-hardening@...ts.openwall.com, linux-hardening@...r.kernel.org, linux-security-module@...r.kernel.org, kernel@...ccoli.net, cascardo@...onical.com, Alexander Potapenko <glider@...gle.com>, James Morris <jamorris@...ux.microsoft.com>, Kees Cook <keescook@...omium.org> Subject: Re: [PATCH] mm, hugetlb: Avoid double clearing for hugetlb pages On 22.10.20 10:55, Michal Hocko wrote: > On Thu 22-10-20 10:04:50, David Hildenbrand wrote: > [...] >>> None of that would address the original point of this thread, the global >>> init_on_alloc parameter. >> >> Yes, but I guess we're past that: whatever leaves the buddy shall be >> zeroed out. That's the whole point of that security hardening mechanism. > > Hugetlb can control its zeroying behavior via mount option (for > MAP_HUGETLB controled by a command line parameter). If the page fault > handler can recognize the pre-initialized pages then both init_on* can Right, looking at init_on_alloc tells you if you have to zero after alloc or if it's already been done even though you didn't pass GFP_ZERO. -- Thanks, David / dhildenb
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