From: Larry Woodman <lwoodman@redhat.com>
Subject: [RHEL5 patch] prevent /proc/meminfo's HugePages_Rsvd from going negative.
Date: Mon, 04 Dec 2006 13:23:59 -0500
Bugzilla: 217910
Message-Id: <457467BF.8090609@redhat.com>
Changelog: prevent /proc/meminfo's HugePages_Rsvd from going negative.


Backported upstream patch to prevent HugePages_Rsvd from going negative:

If you truncate an mmap'ed hugetlbfs file, then fault on the truncated
area, /proc/meminfo's HugePages_Rsvd goes hugely "negative".

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Fixes BZ 217910.




--- linux-2.6.18.noarch/mm/hugetlb.c.orig
+++ linux-2.6.18.noarch/mm/hugetlb.c
@@ -454,6 +454,9 @@ int hugetlb_no_page(struct mm_struct *mm
 retry:
 	page = find_lock_page(mapping, idx);
 	if (!page) {
+		size = i_size_read(mapping->host) >> HPAGE_SHIFT;
+		if (idx >= size)
+			goto out;
 		if (hugetlb_get_quota(mapping))
 			goto out;
 		page = alloc_huge_page(vma, address);