[PATCH] hugetlbfs mmap ENOMEM failure

2.6.15's hugepage faulting introduced huge_pages_needed accounting into
hugetlbfs: to count how many pages are already in cache, for spot check
on how far a new mapping may be allowed to extend the file.  But it's
muddled: each hugepage found covers HPAGE_SIZE, not PAGE_SIZE.  Once
pages were already in cache, it would overshoot, wrap its hugepages
count backwards, and so fail a harmless repeat mapping with -ENOMEM.
Fixes the problem found by Don Dupuis.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-By: Adam Litke <agl@us.ibm.com>
Acked-by: William Irwin <wli@us.ibm.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 8c1cef3bb677015bb1de08922b6b21cc35055f2e..c95ae294b8101c0005bf4f9fb2a6b9727da39421 100644 (file)
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -71,8 +71,8 @@ huge_pages_needed(struct address_space *mapping, struct vm_area_struct *vma)
        unsigned long start = vma->vm_start;
        unsigned long end = vma->vm_end;
        unsigned long hugepages = (end - start) >> HPAGE_SHIFT;
-       pgoff_t next = vma->vm_pgoff;
-       pgoff_t endpg = next + ((end - start) >> PAGE_SHIFT);
+       pgoff_t next = vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT);
+       pgoff_t endpg = next + hugepages;
 
        pagevec_init(&pvec, 0);
        while (next < endpg) {