From: Gavin Shan <shangw@linux.vnet.ibm.com>
Date: Tue, 31 Jul 2012 23:46:04 +0000 (-0700)
Subject: mm/sparse: more checks on mem_section number
X-Git-Tag: v3.6-rc1~24^2~9
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=db36a46113e101a8aa2d6ede41e78f2eaabed3f1

mm/sparse: more checks on mem_section number

__section_nr() was implemented to retrieve the corresponding memory
section number according to its descriptor.  It's possible that the
specified memory section descriptor doesn't exist in the global array.  So
add more checking on that and report an error for a wrong case.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/sparse.c b/mm/sparse.c
index fa933f43b2c9..42ca0ea9af1b 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -130,6 +130,8 @@ int __section_nr(struct mem_section* ms)
 		     break;
 	}
 
+	VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
+
 	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 }