linux-kernel - Re: [PATCH v2 2/5] memory-hotplug: update mce_bad

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Date:	Thu, 18 Oct 2012 15:20:08 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Dave Hansen <dave@...ux.vnet.ibm.com>
Cc:	wency@...fujitsu.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, rientjes@...gle.com,
	liuj97@...il.com, len.brown@...el.com, benh@...nel.crashing.org,
	paulus@...ba.org, minchan.kim@...il.com,
	kosaki.motohiro@...fujitsu.com, isimatu.yasuaki@...fujitsu.com,
	Christoph Lameter <cl@...ux.com>
Subject: Re: [PATCH v2 2/5] memory-hotplug: update mce_bad_pages when
 removing the memory

On Wed, 17 Oct 2012 08:09:55 -0700
Dave Hansen <dave@...ux.vnet.ibm.com> wrote:

> Hi Wen,
> 
> > +#ifdef CONFIG_MEMORY_FAILURE
> > +static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
> > +{
> > +	int i;
> > +
> > +	if (!memmap)
> > +		return;
> 
> I guess free_section_usemap() does the same thing.

What does this observation mean?

> > +	for (i = 0; i < PAGES_PER_SECTION; i++) {
> > +		if (PageHWPoison(&memmap[i])) {
> > +			atomic_long_sub(1, &mce_bad_pages);
> > +			ClearPageHWPoison(&memmap[i]);
> > +		}
> > +	}
> > +}
> > +#endif
> > +
> >  void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
> >  {
> >  	struct page *memmap = NULL;
>
> ..
>
> and keep the #ifdef out of sparse_remove_one_section().

yup.

--- a/mm/sparse.c~memory-hotplug-update-mce_bad_pages-when-removing-the-memory-fix
+++ a/mm/sparse.c
@@ -788,6 +788,10 @@ static void clear_hwpoisoned_pages(struc
 		}
 	}
 }
+#else
+static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+}
 #endif
 
 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
@@ -803,10 +807,7 @@ void sparse_remove_one_section(struct zo
 		ms->pageblock_flags = NULL;
 	}
 
-#ifdef CONFIG_MEMORY_FAILURE
 	clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
-#endif
-
 	free_section_usemap(memmap, usemap);
 }
 #endif
_

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