From: Simon Jeons <simon.jeons@gmail.com>
To: Tang Chen <tangchen@cn.fujitsu.com>
Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
linux-mm@kvack.org, paulus@samba.org, hpa@zytor.com,
sparclinux@vger.kernel.org, cl@linux.com,
linux-s390@vger.kernel.org, x86@kernel.org,
linux-acpi@vger.kernel.org, isimatu.yasuaki@jp.fujitsu.com,
linfeng@cn.fujitsu.com, mgorman@suse.de,
kosaki.motohiro@jp.fujitsu.com, rientjes@google.com,
len.brown@intel.com, wency@cn.fujitsu.com, cmetcalf@tilera.com,
glommer@parallels.com, Jianguo Wu <wujianguo@huawei.com>,
yinghai@kernel.org, laijs@cn.fujitsu.com,
linux-kernel@vger.kernel.org, minchan.kim@gmail.com,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v6 00/15] memory-hotplug: hot-remove physical memory
Date: Thu, 31 Jan 2013 20:17:20 -0600 [thread overview]
Message-ID: <1359685040.1303.6.camel@kernel> (raw)
In-Reply-To: <510B20F9.10408@cn.fujitsu.com>
Hi Tang,
On Fri, 2013-02-01 at 09:57 +0800, Tang Chen wrote:
> On 02/01/2013 09:36 AM, Simon Jeons wrote:
> > On Fri, 2013-02-01 at 09:32 +0800, Jianguo Wu wrote:
> >>>
> >>> So if config NUMA, kernel memory will not be linear mapping anymore? For
> >>> example,
> >>>
> >>> Node 0 Node 1
> >>>
> >>> 0 ~ 10G 11G~14G
>
> It has nothing to do with linear mapping, I think.
>
> >>>
> >>> kernel memory only at Node 0? Can part of kernel memory also at Node 1?
>
> Please refer to find_zone_movable_pfns_for_nodes().
I see, thanks. :)
> The kernel is not only on node0. It uses all the online nodes evenly. :)
>
> >>>
> >>> How big is kernel direct mapping memory in x86_64? Is there max limit?
> >>
> >>
> >> Max kernel direct mapping memory in x86_64 is 64TB.
> >
> > For example, I have 8G memory, all of them will be direct mapping for
> > kernel? then userspace memory allocated from where?
>
> I think you misunderstood what Wu tried to say. :)
>
> The kernel mapped that large space, it doesn't mean it is using that
> large space.
> The mapping is to make kernel be able to access all the memory, not for
> the kernel
> to use only. User space can also use the memory, but each process has
> its own mapping.
>
> For example:
>
> 64TB, what ever
> xxxTB, what ever
> logic address space: |_____kernel_______|_________user_________________|
> \ \ / /
> \ /\ /
> physical address space: |___\/__\/_____________| 4GB or
> 8GB, what ever
> *****
How much address space user process can have on x86_64? Also 8GB?
>
> The ***** part physical is mapped to user space in the process' own
> pagetable.
> It is also direct mapped in kernel's pagetable. So the kernel can also
> access it. :)
But how to protect user process not modify kernel memory?
>
> >
> >>
> >>> It seems that only around 896MB on x86_32.
> >>>
> >>>>
> >>>> We need firmware take part in, such as SRAT in ACPI BIOS, or the firmware
> >>>> based memory migration mentioned by Liu Jiang.
> >>>
> >>> Is there any material about firmware based memory migration?
>
> No, I don't have any because this is a functionality of machine from HUAWEI.
> I think you can ask Liu Jiang or Wu Jianguo to share some with you. :)
>
> Thanks. :)
next prev parent reply other threads:[~2013-02-01 2:48 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-09 9:32 [PATCH v6 00/15] memory-hotplug: hot-remove physical memory Tang Chen
2013-01-09 9:32 ` [PATCH v6 01/15] memory-hotplug: try to offline the memory twice to avoid dependence Tang Chen
2013-01-09 9:32 ` [PATCH v6 02/15] memory-hotplug: check whether all memory blocks are offlined or not when removing memory Tang Chen
2013-01-09 23:11 ` Andrew Morton
2013-01-10 5:56 ` Tang Chen
2013-01-09 9:32 ` [PATCH v6 03/15] memory-hotplug: remove redundant codes Tang Chen
2013-01-09 9:32 ` [PATCH v6 04/15] memory-hotplug: remove /sys/firmware/memmap/X sysfs Tang Chen
2013-01-09 22:49 ` Andrew Morton
2013-01-10 6:07 ` Tang Chen
2013-01-09 23:19 ` Andrew Morton
2013-01-10 6:15 ` Tang Chen
2013-01-09 9:32 ` [PATCH v6 05/15] memory-hotplug: introduce new function arch_remove_memory() for removing page table depends on architecture Tang Chen
2013-01-09 22:50 ` Andrew Morton
2013-01-10 2:25 ` Tang Chen
2013-01-09 9:32 ` [PATCH v6 06/15] memory-hotplug: implement register_page_bootmem_info_section of sparse-vmemmap Tang Chen
2013-01-09 9:32 ` [PATCH v6 07/15] memory-hotplug: move pgdat_resize_lock into sparse_remove_one_section() Tang Chen
2013-01-09 9:32 ` [PATCH v6 08/15] memory-hotplug: Common APIs to support page tables hot-remove Tang Chen
2013-01-29 13:02 ` Simon Jeons
2013-01-30 1:53 ` Jianguo Wu
2013-01-30 2:13 ` Simon Jeons
2013-01-29 13:04 ` Simon Jeons
2013-01-30 2:16 ` Tang Chen
2013-01-30 3:27 ` Simon Jeons
2013-01-30 5:55 ` Tang Chen
2013-01-30 7:32 ` Simon Jeons
2013-02-04 23:04 ` Andrew Morton
2013-01-09 9:32 ` [PATCH v6 09/15] memory-hotplug: remove page table of x86_64 architecture Tang Chen
2013-01-09 9:32 ` [PATCH v6 10/15] memory-hotplug: remove memmap of sparse-vmemmap Tang Chen
2013-01-09 9:32 ` [PATCH v6 11/15] memory-hotplug: Integrated __remove_section() of CONFIG_SPARSEMEM_VMEMMAP Tang Chen
2013-01-09 9:32 ` [PATCH v6 12/15] memory-hotplug: memory_hotplug: clear zone when removing the memory Tang Chen
2013-01-09 9:32 ` [PATCH v6 13/15] memory-hotplug: remove sysfs file of node Tang Chen
2013-01-09 9:32 ` [PATCH v6 14/15] memory-hotplug: free node_data when a node is offlined Tang Chen
2013-01-09 9:32 ` [PATCH v6 15/15] memory-hotplug: Do not allocate pdgat if it was not freed when offline Tang Chen
2013-01-09 22:23 ` [PATCH v6 00/15] memory-hotplug: hot-remove physical memory Andrew Morton
2013-01-10 2:17 ` Tang Chen
2013-01-10 7:14 ` Glauber Costa
2013-01-10 7:31 ` Kamezawa Hiroyuki
2013-01-10 7:55 ` Glauber Costa
2013-01-10 8:23 ` Kamezawa Hiroyuki
2013-01-10 8:36 ` Glauber Costa
2013-01-10 8:39 ` Kamezawa Hiroyuki
2013-01-09 23:33 ` Andrew Morton
2013-01-10 2:18 ` Tang Chen
2013-01-29 12:52 ` Simon Jeons
2013-01-30 2:32 ` Tang Chen
2013-01-30 2:48 ` Simon Jeons
2013-01-30 3:00 ` Tang Chen
2013-01-30 10:15 ` Tang Chen
2013-01-30 10:18 ` Tang Chen
2013-01-31 1:22 ` Simon Jeons
2013-01-31 3:31 ` Tang Chen
2013-01-31 6:19 ` Simon Jeons
2013-01-31 7:10 ` Tang Chen
2013-01-31 8:17 ` Simon Jeons
2013-01-31 8:48 ` Simon Jeons
2013-01-31 9:44 ` Tang Chen
2013-01-31 10:38 ` Simon Jeons
2013-02-01 1:32 ` Jianguo Wu
2013-02-01 1:36 ` Simon Jeons
2013-02-01 1:57 ` Jianguo Wu
2013-02-01 2:06 ` Simon Jeons
2013-02-01 2:18 ` Jianguo Wu
2013-02-01 1:57 ` Tang Chen
2013-02-01 2:17 ` Simon Jeons [this message]
2013-02-01 2:42 ` Tang Chen
2013-02-01 3:06 ` Simon Jeons
2013-02-01 3:39 ` Tang Chen
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