[PATCH] hugetlb: fix absurd HugePages_Rsvd

If you truncated an mmap'ed hugetlbfs file, then faulted on the truncated
area, /proc/meminfo's HugePages_Rsvd wrapped hugely "negative".  Reinstate my
preliminary i_size check before attempting to allocate the page (though this
only fixes the most obvious case: more work will be needed here).

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>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2dbec90dc3ba..a088f593a807 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -478,6 +478,9 @@ int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
 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);