linux-kernel - Re: [7/7,v8] NUMA Hotplug Emulator: Implement per-node add

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]

Message-ID: <20101213020924.GB19637@shaohui>
Date:	Mon, 13 Dec 2010 10:09:25 +0800
From:	Shaohui Zheng <shaohui.zheng@...ux.intel.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, haicheng.li@...ux.intel.com,
	lethal@...ux-sh.org, Andi Kleen <ak@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [7/7,v8] NUMA Hotplug Emulator: Implement per-node add_memory
 debugfs interface

On Fri, Dec 10, 2010 at 03:30:38PM -0800, David Rientjes wrote:
> On Fri, 10 Dec 2010, Shaohui Zheng wrote:
> 
> > > That doesn't address the question.  My question is whether or not adding 
> > > memory to a memoryless node in this way transitions its state to 
> > > N_HIGH_MEMORY in the VM?
> > I guess that you are talking about memory hotplug on x86_32, memory hotplug is
> > NOT supported well for x86_32, and the function add_memory does not consider
> > this situlation.
> > 
> > For 64bit, N_HIGH_MEMORY == N_NORMAL_MEMORY, so we need not to do the transition.
> > 
> 
> One more time :)  Memoryless nodes do not have their bit set in 
> N_HIGH_MEMORY.  When memory is added to a memoryless node with this new 
> interface, does the bit get set?

When we use debugfs add_node interface to add a fake node, the node was created, 
and memory sections were created, but the state of the memory section is still 
__offline__, so the new added node is still memoryless node. the result of debugfs
add_memory interface doing the similar thing with add_node, it just add memory
to an exists node.

For the state transition to N_HIGH_MEMORY, it does not happen on the above too
interfaces. It happens when the memory was onlined with sysfs /sys/device/system/memory/memoryXX/online
interface.

That is the code path:
store_mem_state
	->memory_block_change_state
	 	->memory_block_action
			->online_pages

			if (onlined_pages) {
				kswapd_run(zone_to_nid(zone));
				node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
			}

does it address your question? thanks.

-- 
Thanks & Regards,
Shaohui

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/