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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2014-07-23 14:00:19 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-31 12:44:09 -0700
commitdd8fca578cc01b181dddd05eee521f6c62ec4ca3 (patch)
treeca1453125418ac4235f5336ce65c9f071a77c7b9
parentae6cea4f9a49eda3ee02826d9578db66350f2ad5 (diff)
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 <unistd.h> #include <stdlib.h> #include <string.h> #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 <n-horiguchi@ah.jp.nec.com> Reported-by: Guillaume Morin <guillaume@morinfr.org> Suggested-by: Guillaume Morin <guillaume@morinfr.org> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--mm/hugetlb.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a646f1598d58..002f08e3d61c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2461,6 +2461,7 @@ 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);