From: "H. Peter Anvin" <hpa@zytor.com>
To: Tang Chen <tangchen@cn.fujitsu.com>
Cc: rjw@sisk.pl, lenb@kernel.org, tglx@linutronix.de, mingo@elte.hu,
akpm@linux-foundation.org, tj@kernel.org, trenn@suse.de,
yinghai@kernel.org, jiang.liu@huawei.com, wency@cn.fujitsu.com,
laijs@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com,
izumi.taku@jp.fujitsu.com, mgorman@suse.de, minchan@kernel.org,
mina86@mina86.com, gong.chen@linux.intel.com,
vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com,
riel@redhat.com, jweiner@redhat.com, prarit@redhat.com,
zhangyanfei@cn.fujitsu.com, yanghy@cn.fujitsu.com,
x86@kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-acpi@vger.kernel.org
Subject: Re: [PATCH v2 00/18] Arrange hotpluggable memory as ZONE_MOVABLE.
Date: Mon, 05 Aug 2013 06:07:31 -0700 [thread overview]
Message-ID: <51FFA393.2080301@zytor.com> (raw)
In-Reply-To: <1375340800-19332-1-git-send-email-tangchen@cn.fujitsu.com>
On 08/01/2013 12:06 AM, Tang Chen wrote:
> This patch-set aims to solve some problems at system boot time
> to enhance memory hotplug functionality.
>
> [Background]
>
> The Linux kernel cannot migrate pages used by the kernel because
> of the kernel direct mapping. Since va = pa + PAGE_OFFSET, if the
> physical address is changed, we cannot simply update the kernel
> pagetable. On the contrary, we have to update all the pointers
> pointing to the virtual address, which is very difficult to do.
>
It does beg the question if that "since" statement should be changed ...
we already have it handled differently on Xen PV, but that is kind of
"special". There are a whole bunch of other issues with moving kernel
memory around: you have to worry what might have a physical address
cached somewhere and what might be in active use and so on... I am not
really suggesting it as anything but food for thought at this time.
-hpa
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next prev parent reply other threads:[~2013-08-05 13:08 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-01 7:06 [PATCH v2 00/18] Arrange hotpluggable memory as ZONE_MOVABLE Tang Chen
2013-08-01 7:06 ` [PATCH v2 01/18] acpi: Print Hot-Pluggable Field in SRAT Tang Chen
2013-08-01 21:55 ` Toshi Kani
2013-08-01 7:06 ` [PATCH v2 02/18] earlycpio.c: Fix the confusing comment of find_cpio_data() Tang Chen
2013-08-01 21:57 ` Toshi Kani
2013-08-02 4:48 ` Tang Chen
2013-08-01 7:06 ` [PATCH v2 03/18] acpi: Remove "continue" in macro INVALID_TABLE() Tang Chen
2013-08-01 20:26 ` Rafael J. Wysocki
2013-08-01 22:06 ` Toshi Kani
2013-08-02 1:32 ` Tang Chen
2013-08-01 7:06 ` [PATCH v2 04/18] acpi: Introduce acpi_invalid_table() to check if a table is invalid Tang Chen
2013-08-01 20:27 ` Rafael J. Wysocki
2013-08-01 22:26 ` Toshi Kani
2013-08-02 1:34 ` Tang Chen
2013-08-01 7:06 ` [PATCH v2 05/18] x86, acpi: Split acpi_boot_table_init() into two parts Tang Chen
2013-08-01 23:32 ` Toshi Kani
2013-08-02 5:25 ` Zheng, Lv
2013-08-02 7:01 ` Tang Chen
2013-08-02 8:11 ` Zheng, Lv
2013-08-02 8:23 ` Zheng, Lv
2013-08-02 8:29 ` Tang Chen
2013-08-02 8:54 ` Zheng, Lv
2013-08-02 9:13 ` Tang Chen
2013-08-01 7:06 ` [PATCH v2 06/18] x86, acpi: Initialize ACPI root table list earlier Tang Chen
2013-08-01 23:54 ` Toshi Kani
2013-08-02 7:49 ` Tang Chen
2013-08-02 16:57 ` Toshi Kani
2013-08-01 7:06 ` [PATCH v2 07/18] x86, acpi: Also initialize signature and length when parsing root table Tang Chen
2013-08-02 0:10 ` Toshi Kani
2013-08-02 5:28 ` Zheng, Lv
2013-08-01 7:06 ` [PATCH v2 08/18] x86: get pg_data_t's memory from other node Tang Chen
2013-08-02 0:23 ` Toshi Kani
2013-08-01 7:06 ` [PATCH v2 09/18] x86: Make get_ramdisk_{image|size}() global Tang Chen
2013-08-01 7:06 ` [PATCH v2 10/18] x86, acpi: Try to find if SRAT is overrided earlier Tang Chen
2013-08-02 1:19 ` Toshi Kani
2013-08-02 5:49 ` Tang Chen
2013-08-02 16:05 ` Toshi Kani
2013-08-01 7:06 ` [PATCH v2 11/18] x86, acpi: Try to find SRAT in firmware earlier Tang Chen
2013-08-01 7:06 ` [PATCH v2 12/18] x86, acpi, numa, mem_hotplug: Find hotpluggable memory in SRAT memory affinities Tang Chen
2013-08-01 7:06 ` [PATCH v2 13/18] x86, numa, mem_hotplug: Skip all the regions the kernel resides in Tang Chen
2013-08-01 13:42 ` Tejun Heo
2013-08-02 5:51 ` Tang Chen
2013-08-01 7:06 ` [PATCH v2 14/18] memblock, numa: Introduce flag into memblock Tang Chen
2013-08-01 7:06 ` [PATCH v2 15/18] memblock, mem_hotplug: Introduce MEMBLOCK_HOTPLUG flag to mark hotpluggable regions Tang Chen
2013-08-01 7:06 ` [PATCH v2 16/18] memblock, mem_hotplug: Make memblock skip hotpluggable regions by default Tang Chen
2013-08-01 7:06 ` [PATCH v2 17/18] mem-hotplug: Introduce movablenode boot option to {en|dis}able using SRAT Tang Chen
2013-08-01 7:06 ` [PATCH v2 18/18] x86, numa, acpi, memory-hotplug: Make movablenode have higher priority Tang Chen
2013-08-05 13:07 ` H. Peter Anvin [this message]
2013-08-05 13:38 ` [PATCH v2 00/18] Arrange hotpluggable memory as ZONE_MOVABLE Tang Chen
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