linux-kernel - Re: [RFC][PATCH 5/6] kcore: check physical memory range in correct way.

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Message-ID: <20090728102411.GG6036@cr0.nay.redhat.com>
Date:	Tue, 28 Jul 2009 18:24:11 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	xiyou.wangcong@...il.com,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	ralf@...ux-mips.org, benh@...nel.crashing.org, lethal@...ux-sh.org
Subject: Re: [RFC][PATCH 5/6] kcore: check physical memory range  in
	correct way.

On Fri, Jul 24, 2009 at 05:19:27PM +0900, KAMEZAWA Hiroyuki wrote:
>From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>
>For /proc/kcore, each arch registers its memory range by kclist_add().
>In usual,
>	- range of physical memory
>	- range of vmalloc area
>	- text, etc...
>are registered but "range of physical memory" has some troubles.
>
>It doesn't updated at memory hotplug and it tend to include
>unnecessary memory holes. Now, /proc/iomem (kernel/resource.c)
>includes required physical memory range information and it's
>properly updated at memory hotplug. Then, it's good to avoid
>using its own code(duplicating information) and to rebuild
>kclist for physical memory based on /proc/iomem.
>
>Note: IIUC, /proc/iomem information is used for kdump.
>
>Changelog: v2 -> v3
> - fixed HIGHMEM codes.(At least, no compile error)
> - enhnanced sanity chesk in !HIGHMEM codes. (See kclist_add_private())
> - after this, x86-32, ia64, sh, powerpc has no private kclist codes.
>   x86-64 and mips still have some.


<snip>



>Index: mmotm-2.6.31-Jul16/include/linux/ioport.h
>===================================================================
>--- mmotm-2.6.31-Jul16.orig/include/linux/ioport.h
>+++ mmotm-2.6.31-Jul16/include/linux/ioport.h
>@@ -186,5 +186,13 @@ extern void __devm_release_region(struct
> extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);
> extern int iomem_is_exclusive(u64 addr);
> 
>+/*
>+ * Walk through all SYSTEM_RAM which is registered as resource.
>+ * arg is (start_pfn, nr_pages, private_arg_pointer)
>+ */
>+extern int walk_memory_resource(unsigned long start_pfn,
>+			unsigned long nr_pages, void *arg,
>+			int (*func)(unsigned long, unsigned long, void *));
>+
> #endif /* __ASSEMBLY__ */
> #endif	/* _LINUX_IOPORT_H */
>Index: mmotm-2.6.31-Jul16/include/linux/memory_hotplug.h
>===================================================================
>--- mmotm-2.6.31-Jul16.orig/include/linux/memory_hotplug.h
>+++ mmotm-2.6.31-Jul16/include/linux/memory_hotplug.h
>@@ -191,13 +191,6 @@ static inline void register_page_bootmem
> 
> #endif /* ! CONFIG_MEMORY_HOTPLUG */
> 
>-/*
>- * Walk through all memory which is registered as resource.
>- * arg is (start_pfn, nr_pages, private_arg_pointer)
>- */
>-extern int walk_memory_resource(unsigned long start_pfn,
>-			unsigned long nr_pages, void *arg,
>-			int (*func)(unsigned long, unsigned long, void *));


Why moving it? :)

> 
> #ifdef CONFIG_MEMORY_HOTREMOVE
> 
>Index: mmotm-2.6.31-Jul16/kernel/resource.c
>===================================================================
>--- mmotm-2.6.31-Jul16.orig/kernel/resource.c
>+++ mmotm-2.6.31-Jul16/kernel/resource.c
>@@ -234,7 +234,7 @@ int release_resource(struct resource *ol
> 
> EXPORT_SYMBOL(release_resource);
> 
>-#if defined(CONFIG_MEMORY_HOTPLUG) && !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
>+#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
> /*
>  * Finds the lowest memory reosurce exists within [res->start.res->end)
>  * the caller must specify res->start, res->end, res->flags.


Shouldn't this part be in patch 6/6 instead of this one?
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