linux-kernel - Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_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:   Wed, 24 May 2017 15:30:17 +0200
From:   Igor Mammedov <imammedo@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
        qiuxishi@...wei.com, Kani Toshimitsu <toshi.kani@....com>,
        slaoub@...il.com, Joonsoo Kim <js1304@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

On Wed, 24 May 2017 14:24:11 +0200
Michal Hocko <mhocko@...nel.org> wrote:

[...]
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
[...]
> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
maybe dumb question but, is it really true that kernel won't ever
do kernel allocations from movable zone?

looking at kmalloc(slab): we can get here:

get_page_from_freelist() ->
    rmqueue() ->
        __rmqueue() ->
            __rmqueue_fallback() ->
                find_suitable_fallback()

and it might return movable fallback and page could be stolen from there.