From b9bae3402572dc50a1e084c5b1ae5117918ef0f0 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hugh@veritas.com>
Date: Thu, 21 Jun 2007 23:27:45 +0100
Subject: [PATCH] page_mapping must avoid slub pages

Nicolas Ferre reports oops from flush_dcache_page() on ARM when using
SLUB: which reuses page->mapping as page->slab.  The page_mapping()
function, used by ARM and PA-RISC flush_dcache_page() implementations,
must not confuse SLUB pages with those which have page->mapping set.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Nicolas Ferre <nicolas.ferre@rfo.atmel.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e4183c6c7d..1c1207472b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -603,6 +603,10 @@ static inline struct address_space *page_mapping(struct page *page)
 
 	if (unlikely(PageSwapCache(page)))
 		mapping = &swapper_space;
+#ifdef CONFIG_SLUB
+	else if (unlikely(PageSlab(page)))
+		mapping = NULL;
+#endif
 	else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
 		mapping = NULL;
 	return mapping;
-- 
2.39.5