From 32226c206801036be8d17e183ee51391f601a6cc Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Wed, 23 Jul 2014 14:00:19 -0700 Subject: mm: hugetlb: fix copy_hugetlb_page_range() commit 0253d634e0803a8376a0d88efee0bf523d8673f9 upstream. Commit 4a705fef9862 ("hugetlb: fix copy_hugetlb_page_range() to handle migration/hwpoisoned entry") changed the order of huge_ptep_set_wrprotect() and huge_ptep_get(), which leads to breakage in some workloads like hugepage-backed heap allocation via libhugetlbfs. This patch fixes it. The test program for the problem is shown below: $ cat heap.c #include #include #include #define HPS 0x200000 int main() { int i; char *p = malloc(HPS); memset(p, '1', HPS); for (i = 0; i < 5; i++) { if (!fork()) { memset(p, '2', HPS); p = malloc(HPS); memset(p, '3', HPS); free(p); return 0; } } sleep(1); free(p); return 0; } $ export HUGETLB_MORECORE=yes ; export HUGETLB_NO_PREFAULT= ; hugectl --heap ./heap Fixes 4a705fef9862 ("hugetlb: fix copy_hugetlb_page_range() to handle migration/hwpoisoned entry"), so is applicable to -stable kernels which include it. Signed-off-by: Naoya Horiguchi Reported-by: Guillaume Morin Suggested-by: Guillaume Morin Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb.c | 1 + 1 file changed, 1 insertion(+) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index dbc949c409c7..7de4f67c81fe 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2400,6 +2400,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, } else { if (cow) huge_ptep_set_wrprotect(src, addr, src_pte); + entry = huge_ptep_get(src_pte); ptepage = pte_page(entry); get_page(ptepage); page_dup_rmap(ptepage); -- cgit v1.2.3