From a425a638c858fd10370b573bde81df3ba500e271 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 5 May 2009 16:37:17 +0100 Subject: [PATCH] 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 Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- mm/madvise.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/madvise.c b/mm/madvise.c index b9ce574827c8..36d6ea2b6340 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -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;