From: Baoquan He <bhe@redhat.com>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Tejun Heo <tj@kernel.org>, Pingfan Liu <kernelfans@gmail.com>,
linux-acpi@vger.kernel.org, linux-mm@kvack.org,
kexec@lists.infradead.org, Tang Chen <tangchen@cn.fujitsu.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Michal Hocko <mhocko@suse.com>, Jonathan Corbet <corbet@lwn.net>,
Yaowei Bai <baiyaowei@cmss.chinamobile.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
Nicholas Piggin <npiggin@gmail.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Daniel Vacek <neelx@redhat.com>,
Mathieu Malaterre <malat@debian.org>,
Stefan Agner <stefan@agner.ch>, Dave Young <dyoung@redhat.com>,
yinghai@kernel.org, vgoyal@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr
Date: Tue, 8 Jan 2019 16:50:02 +0800 [thread overview]
Message-ID: <20190108085002.GA18718@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20190106062733.GA3728@rapoport-lnx>
On 01/06/19 at 08:27am, Mike Rapoport wrote:
> I do not suggest to discard the bottom-up method, I merely suggest to allow
> it to use [0, kernel_start).
Sorry for late reply.
I misunderstood it, sorry.
> > This bottom-up way is taken on many ARCHes, it works well on system if
> > KASLR is not enabled. Below is the searching result in the current linux
> > kernel, we can see that all ARCHes have this mechanism, except of
> > arm/arm64. But now only arm64/mips/x86 have KASLR.
> >
> > W/o KASLR, allocating memblock region above kernle end when hotplug info
> > is not parsed, looks very reasonable. Since kernel is usually put at
> > lower address, e.g on x86, it's 16M. My thought is that we need do
> > memblock allocation around kernel before hotplug info parsed. That is
> > for system w/o KASLR, we will keep the current bottom-up way; for system
> > with KASLR, we should allocate memblock region top-down just below
> > kernel start.
>
> I completely agree. I was thinking about making
> memblock_find_in_range_node() to do something like
>
> if (memblock_bottom_up()) {
> bottom_up_start = max(start, kernel_end);
In this way, if start < kernel_end, it will still succeed to find a
region in bottom-up way after kernel end.
I am still reading code. Just noticed Pingfan sent a RFC patchset to put
SRAT parsing earlier, not sure if he has tested it in numa system with
acpi. I doubt that really works.
Thanks
Baoquan
> ret = __memblock_find_range_bottom_up(bottom_up_start, end,
> size, align, nid, flags);
> if (ret)
> return ret;
>
> bottom_up_start = max(start, 0);
> end = kernel_start;
>
> ret = __memblock_find_range_top_down(bottom_up_start, end,
> size, align, nid, flags);
> if (ret)
> return ret;
> }
next prev parent reply other threads:[~2019-01-08 8:50 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-28 3:00 [PATCHv3 0/2] mm/memblock: reuse memblock bottom-up allocation style Pingfan Liu
2018-12-28 3:00 ` [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr Pingfan Liu
2018-12-31 8:40 ` Mike Rapoport
2019-01-02 6:47 ` Pingfan Liu
2019-01-02 9:27 ` Mike Rapoport
2019-01-02 10:18 ` Baoquan He
2019-01-02 17:05 ` Mike Rapoport
2019-01-03 18:47 ` Tejun Heo
2019-01-04 15:09 ` Mike Rapoport
2019-01-05 3:44 ` Baoquan He
2019-01-06 6:27 ` Mike Rapoport
2019-01-08 8:50 ` Baoquan He [this message]
2019-01-07 8:37 ` Pingfan Liu
2019-01-04 5:59 ` Pingfan Liu
2019-01-04 16:20 ` Mike Rapoport
2018-12-28 3:00 ` [PATCHv3 2/2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Pingfan Liu
2018-12-31 8:46 ` Mike Rapoport
2019-01-02 6:47 ` Pingfan Liu
2019-01-02 9:28 ` Mike Rapoport
2018-12-28 3:39 ` [PATCHv3 0/2] mm/memblock: reuse memblock bottom-up allocation style Baoquan He
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