Commit a425a638 authored May 05, 2009 by Mel Gorman Committed by Linus Torvalds May 05, 2009

Ignore madvise(MADV_WILLNEED) for hugetlbfs-backed regions



madvise(MADV_WILLNEED) forces page cache readahead on a range of memory
backed by a file.  The assumption is made that the page required is
order-0 and "normal" page cache.

On hugetlbfs, this assumption is not true and order-0 pages are
allocated and inserted into the hugetlbfs page cache.  This leaks
hugetlbfs page reservations and can cause BUGs to trigger related to
corrupted page tables.

This patch causes MADV_WILLNEED to be ignored for hugetlbfs-backed
regions.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 99ee1297

mm/madvise.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -112,6 +112,14 @@ static long madvise_willneed(struct vm_area_struct * vma,
		if (!file)
		return -EBADF;

		/*
		* Page cache readahead assumes page cache pages are order-0 which
		* is not the case for hugetlbfs. Do not give a bad return value
		* but ignore the advice.
		*/
		if (vma->vm_flags & VM_HUGETLB)
		return 0;

		if (file->f_mapping->a_ops->get_xip_mem) {
		/* no bad return value, but ignore advice */
		return 0;

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