From 64b4a954b03a1153fb8ae38d6ffbd991e01a1e80 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sat, 4 Feb 2006 23:27:55 -0800 Subject: [PATCH] [PATCH] hugetlb: add comment explaining reasons for Bus Errors I just spent some time researching a Bus Error. Turns out that the huge page fault handler can return VM_FAULT_SIGBUS for various conditions where no huge page is available. Add a note explaining the reasoning in the source. Signed-off-by: Christoph Lameter Acked-by: William Lee Irwin III Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index b21d78c941b5..ceb3ebb3c399 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -444,6 +444,15 @@ retry: page = alloc_huge_page(vma, address); if (!page) { hugetlb_put_quota(mapping); + /* + * No huge pages available. So this is an OOM + * condition but we do not want to trigger the OOM + * killer, so we return VM_FAULT_SIGBUS. + * + * A program using hugepages may fault with Bus Error + * because no huge pages are available in the cpuset, per + * memory policy or because all are in use! + */ goto out; }