linux-kernel - Re: [PATCH 1/6] acpi, numa, mem_hotplug: Kill save_add

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Message-ID: <1376938080.10300.453.camel@misato.fc.hp.com>
Date:	Mon, 19 Aug 2013 12:48:00 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Tang Chen <tangchen@...fujitsu.com>
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	lenb@...nel.org, rjw@...k.pl, liwanp@...ux.vnet.ibm.com,
	tj@...nel.org, akpm@...ux-foundation.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH 1/6] acpi, numa, mem_hotplug: Kill save_add_info().

On Fri, 2013-08-16 at 15:06 +0800, Tang Chen wrote:
> save_add_info() is defined as:
> 
> 	#ifdef CONFIG_MEMORY_HOTPLUG
> 	static inline int save_add_info(void) {return 1;}
> 	#else
> 	static inline int save_add_info(void) {return 0;}
> 	#endif
> 
> which means it is true when memory hotplug is configured.
> 
> In acpi_numa_memory_affinity_init(), it checks the memory hotplug
> flag in SRAT memory affinity and save_add_info() like this:
> 
> 	if ((ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && !save_add_info())
> 		goto out_err;
> 	......
> 	node = setup_node(pxm);
> 	numa_add_memblk(node, start, end);
> 	......
> 
> which means if the memory range is hotpluggable, but memory hotplug is not
> configured, it won't add these memory to numa_meminfo.
> 
> After this, numa_meminfo_cover_memory() will fail, which will finally cause
> numa_init() to fail.
> 
> numa_init()
>  |->numa_register_memblks()
>      |->numa_meminfo_cover_memory()
> 
> When numa_init() fails, it will fallback to numa_init(dummy_numa_init), and
> all numa architecture will not be setup.
> 
> This is nonsense. Even if memory hotplug is not configured, we can also use
> numa architecture.
> 
> Actually, save_add_info() is added by commit 71efa8fdc55e70ec6687c897a30759f0a2c2ad7e
> in 2006. And now it is useless.
> 
> So this patch kill save_add_info() and the nonsense checking.
> 
> Signed-off-by: Tang Chen <tangchen@...fujitsu.com>

Good catch!

Acked-by: Toshi Kani <toshi.kani@...com>

Thanks,
-Toshi

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