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  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:   Wed, 13 Feb 2019 12:27:29 +0100
From:   Vlastimil Babka <>
To:     Alexandre Ghiti <>,
        Catalin Marinas <>,
        Will Deacon <>,
        Benjamin Herrenschmidt <>,
        Paul Mackerras <>,
        Michael Ellerman <>,
        Martin Schwidefsky <>,
        Heiko Carstens <>,
        Thomas Gleixner <>,
        Ingo Molnar <>, Borislav Petkov <>,
        "H . Peter Anvin" <>,,
        Alexander Viro <>,
        Mike Kravetz <>,,,,,,
        Alexandre Ghiti <>
Subject: Re: [PATCH] hugetlb: allow to free gigantic pages regardless of the

On 1/17/19 7:39 PM, Alexandre Ghiti wrote:
> From: Alexandre Ghiti <>
> On systems without CMA or (MEMORY_ISOLATION && COMPACTION) activated but
> that support gigantic pages, boottime reserved gigantic pages can not be
> freed at all. This patchs simply enables the possibility to hand back
> those pages to memory allocator.
> This commit then renames gigantic_page_supported and
> ARCH_HAS_GIGANTIC_PAGE to make them more accurate. Indeed, those values
> being false does not mean that the system cannot use gigantic pages: it
> just means that runtime allocation of gigantic pages is not supported,
> one can still allocate boottime gigantic pages if the architecture supports
> it.
> Signed-off-by: Alexandre Ghiti <>

I'm fine with the change, but wonder if this can be structured better in a way
which would remove the duplicated "if (MEMORY_ISOLATION && COMPACTION) || CMA"
from all arches, as well as the duplicated

something like:

- "select ARCH_HAS_GIGANTIC_PAGE" has no conditions, it just says the arch can
support them either at boottime or runtime (but runtime is usable only if other
conditions are met)
- gigantic_page_runtime_allocation_supported() is a function that returns true
there's a single instance, not per-arch.
- code for freeing gigantic pages can probably still be conditional on

BTW I wanted also to do something about the "(MEMORY_ISOLATION && COMPACTION) ||
CMA" ugliness itself, i.e. put the common parts behind some new kconfig
(COMPACTION_CORE ?) and expose it better to users, but I can take a stab on that
once the above part is settled.


Powered by blists - more mailing lists