linux-kernel - Re: [PATCH v7 2/5] mm: remove x86-only restriction of movable

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, 15 Nov 2016 12:35:42 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
        devicetree@...r.kernel.org,
        Bharata B Rao <bharata@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        Stewart Smith <stewart@...ux.vnet.ibm.com>,
        Alistair Popple <apopple@....ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/5] mm: remove x86-only restriction of movable_node

Reza Arbab <arbab@...ux.vnet.ibm.com> writes:

> In commit c5320926e370 ("mem-hotplug: introduce movable_node boot
> option"), the memblock allocation direction is changed to bottom-up and
> then back to top-down like this:
>
> 1. memblock_set_bottom_up(true), called by cmdline_parse_movable_node().
> 2. memblock_set_bottom_up(false), called by x86's numa_init().
>
> Even though (1) occurs in generic mm code, it is wrapped by #ifdef
> CONFIG_MOVABLE_NODE, which depends on X86_64.
>
> This means that when we extend CONFIG_MOVABLE_NODE to non-x86 arches,
> things will be unbalanced. (1) will happen for them, but (2) will not.
>
> This toggle was added in the first place because x86 has a delay between
> adding memblocks and marking them as hotpluggable. Since other arches do
> this marking either immediately or not at all, they do not require the
> bottom-up toggle.
>
> So, resolve things by moving (1) from cmdline_parse_movable_node() to
> x86's setup_arch(), immediately after the movable_node parameter has
> been parsed.


Considering that we now can mark memblock hotpluggable, do we need to
enable the bottom up allocation for ppc64 also ?


>
> Signed-off-by: Reza Arbab <arbab@...ux.vnet.ibm.com>
> ---
>  Documentation/kernel-parameters.txt |  2 +-
>  arch/x86/kernel/setup.c             | 24 ++++++++++++++++++++++++

-aneesh