Commit 4e6a510a authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds

[PATCH] mm: hugepage accounting fix

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: default avatarHugh Dickins <>
Acked-By: default avatarAdam Litke <>
Acked-by: default avatarWilliam Irwin <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 9884fd8d
......@@ -72,8 +72,8 @@ 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) {
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