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Date: Fri, 23 Oct 2020 10:23:07 +0200
From: David Hildenbrand <>
To: Michal Hocko <>
Cc: Mike Kravetz <>,
 "Guilherme G. Piccoli" <>,,,,,,, Alexander Potapenko <>,
 James Morris <>,
 Kees Cook <>
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.


David / dhildenb

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