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

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Message-Id: <20090729085810.c1a6b75a.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 29 Jul 2009 08:58:10 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Amerigo Wang <xiyou.wangcong@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"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 Tue, 28 Jul 2009 18:24:11 +0800
Amerigo Wang <xiyou.wangcong@...il.com> wrote:

> 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? :)
> 
Ah, this declaration is in memory_hotplug.h because it's only for memory
hotplug. For generic use, it's better to move this to iomem.h as other
resource related ops, I think.



> > 
> > #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?
> 
Hmm, ok, I'll reorder 5/6 and 6/6 and define walk_system_ram_range() before
this patch.

Thanks,
-Kame

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