linux-kernel - Re: [RFC PATCH 0/3] create hugetlb flags to consolidate state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 12 Jan 2021 11:41:04 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     Michal Hocko <mhocko@...nel.org>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Muchun Song <songmuchun@...edance.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC PATCH 0/3] create hugetlb flags to consolidate state

On 11.01.21 22:01, Mike Kravetz wrote:
> While discussing a series of hugetlb fixes in [1], it became evident
> that the hugetlb specific page state information is stored in a somewhat
> haphazard manner.  Code dealing with state information would be easier
> to read, understand and maintain if this information was stored in a
> consistent manner.
> 
> This RFC series uses page.private of the hugetlb head page for storing a
> set of hugetlb specific page flags.  Routines to manipulate the flags
> are copied from normal page flag manipulation code and use atomic
> operations.  This is likely overkill for the uses in hugetlb code, and
> can be changed after additional auditing of code.

Haven't looked into the code but that sounds like a good idea.

> 
> For now, only 3 state flags are added as part of this series.  However,
> the suggested fix in [2] could use another flag.  In addition, a flag
> could be used to track whether or not a huge page has been cleared to
> optimize code paths if the init_on_alloc security feature is enabled.

Right, that will be helpful: indicating pages that were either cleared
directly when allocating (init_on_alloc) or via some asynchronous
mechanism in the future.

-- 
Thanks,

David / dhildenb