Commit 4e6a510a authored Feb 01, 2006 by Hugh Dickins Committed by Linus Torvalds Feb 01, 2006

[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: Hugh Dickins <hugh@veritas.com>
Acked-By: Adam Litke <agl@us.ibm.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 9884fd8d

fs/hugetlbfs/inode.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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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