From: Michal Hocko <mhocko@kernel.org>
To: Baoquan He <bhe@redhat.com>
Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>,
Dou Liyang <douly.fnst@cn.fujitsu.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, x86@kernel.org,
yasu.isimatu@gmail.com, keescook@chromium.org,
indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com,
vbabka@suse.cz, mgorman@techsingularity.net
Subject: Re: Bug report about KASLR and ZONE_MOVABLE
Date: Mon, 16 Jul 2018 13:38:45 +0200 [thread overview]
Message-ID: <20180716113845.GM17280@dhcp22.suse.cz> (raw)
In-Reply-To: <20180712235240.GH2070@MiWiFi-R3L-srv>
On Fri 13-07-18 07:52:40, Baoquan He wrote:
> Hi Michal,
>
> On 07/12/18 at 02:32pm, Michal Hocko wrote:
[...]
> > I am not able to find the beginning of the email thread right now. Could
> > you summarize what is the actual problem please?
>
> The bug is found on x86 now.
>
> When added "kernelcore=" or "movablecore=" into kernel command line,
> kernel memory is spread evenly among nodes. However, this is right when
> KASLR is not enabled, then kernel will be at 16M of place in x86 arch.
> If KASLR enabled, it could be put any place from 16M to 64T randomly.
>
> Consider a scenario, we have 10 nodes, and each node has 20G memory, and
> we specify "kernelcore=50%", means each node will take 10G for
> kernelcore, 10G for movable area. But this doesn't take kernel position
> into consideration. E.g if kernel is put at 15G of 2nd node, namely
> node1. Then we think on node1 there's 10G for kernelcore, 10G for
> movable, in fact there's only 5G available for movable, just after
> kernel.
OK, I guess I see that part. But who is going to use movablecore along
with KASLR enabled? I mean do we really have to support those two
obscure command line parameters for KASLR?
In fact I would be much more concerned about memory hotplug and
pre-defined movable nodes. Does the current KASLR code work in that
case?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-07-16 11:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 9:42 Bug report about KASLR and ZONE_MOVABLE Chao Fan
2018-07-11 10:04 ` Chao Fan
2018-07-11 10:16 ` Chao Fan
2018-07-11 10:41 ` Baoquan He
2018-07-11 10:49 ` Baoquan He
2018-07-11 12:40 ` Baoquan He
2018-07-11 17:59 ` [PATCH v3] mm, page_alloc: find movable zone after kernel text kbuild test robot
2018-07-11 19:02 ` kbuild test robot
2018-07-12 1:19 ` Bug report about KASLR and ZONE_MOVABLE Chao Fan
2018-07-12 12:08 ` Baoquan He
2018-07-12 5:49 ` Dou Liyang
2018-07-12 6:01 ` Chao Fan
2018-07-12 12:32 ` Michal Hocko
2018-07-12 23:52 ` Baoquan He
2018-07-13 1:44 ` Chao Fan
2018-07-16 11:38 ` Michal Hocko [this message]
2018-07-16 13:02 ` Baoquan He
2018-07-16 15:24 ` Michal Hocko
2018-07-17 1:51 ` Baoquan He
2018-07-17 8:22 ` Michal Hocko
2018-07-11 12:41 ` Baoquan He
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