linux-kernel - [PATCH] mm, sparse: Put clear_hwpoisoned_pages within CONFIG_MEMORY

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Date:	Tue, 18 Jun 2013 22:31:45 +0800
From:	Zhang Yanfei <zhangyanfei.yes@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>
CC:	Linux MM <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	toshi.kani@...com
Subject: [PATCH] mm, sparse: Put clear_hwpoisoned_pages within CONFIG_MEMORY_HOTREMOVE

From: Zhang Yanfei <zhangyanfei@...fujitsu.com>

With CONFIG_MEMORY_HOTREMOVE unset, there is a compile warning:

mm/sparse.c:755: warning: ‘clear_hwpoisoned_pages’ defined but not used

And Bisecting it ended up pointing to:

commit 4edd7ceff0662afde195da6f6c43e7cbe1ed2dc4
Author: David Rientjes <rientjes@...gle.com>
Date:   Mon Apr 29 15:08:22 2013 -0700

    mm, hotplug: avoid compiling memory hotremove functions when disabled
    
    __remove_pages() is only necessary for CONFIG_MEMORY_HOTREMOVE.  PowerPC
    pseries will return -EOPNOTSUPP if unsupported.
    
    Adding an #ifdef causes several other functions it depends on to also
    become unnecessary, which saves in .text when disabled (it's disabled in
    most defconfigs besides powerpc, including x86).  remove_memory_block()
    becomes static since it is not referenced outside of
    drivers/base/memory.c.
    
    Build tested on x86 and powerpc with CONFIG_MEMORY_HOTREMOVE both enabled
    and disabled.
    
    Signed-off-by: David Rientjes <rientjes@...gle.com>
    Acked-by: Toshi Kani <toshi.kani@...com>
    Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
    Cc: Paul Mackerras <paulus@...ba.org>
    Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
    Cc: Wen Congyang <wency@...fujitsu.com>
    Cc: Tang Chen <tangchen@...fujitsu.com>
    Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
    Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>

This is because the commit above put function sparse_remove_one_section
within the protection of CONFIG_MEMORY_HOTREMOVE but the only user of
function clear_hwpoisoned_pages is sparse_remove_one_section, and it
is not within the protection of CONFIG_MEMORY_HOTREMOVE.

So put clear_hwpoisoned_pages within CONFIG_MEMORY_HOTREMOVE should
fix the warning.

Signed-off-by: Zhang Yanfei <zhangyanfei@...fujitsu.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Toshi Kani <toshi.kani@...com>
---
 mm/sparse.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 1c91f0d..999a1fe 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -751,6 +751,7 @@ out:
 	return ret;
 }
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
 #ifdef CONFIG_MEMORY_FAILURE
 static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 {
@@ -772,7 +773,6 @@ static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 }
 #endif
 
-#ifdef CONFIG_MEMORY_HOTREMOVE
 static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 {
 	struct page *usemap_page;
-- 
1.7.1
--
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