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Ignore madvise(MADV_WILLNEED) for hugetlbfs-backed regions

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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>
This commit is contained in:
Mel Gorman 2009-05-05 16:37:17 +01:00 committed by Linus Torvalds
parent 99ee12973e
commit a425a638c8
1 changed files with 8 additions and 0 deletions
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8
mm/madvise.c
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@ -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;