thp: prevent hugepages during args/env copying into the user stack

Transparent hugepages can only be created if rmap is fully
functional. So we must prevent hugepages to be created while
is_vma_temporary_stack() is true.

This also optmizes away some harmless but unnecessary setting of
khugepaged_scan.address and it switches some BUG_ON to VM_BUG_ON.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 8e6c8c42bc3..df29c8fde36 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -57,7 +57,8 @@ extern pmd_t *page_check_address_pmd(struct page *page,
           (transparent_hugepage_flags &                                 \
            (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) &&                   \
            ((__vma)->vm_flags & VM_HUGEPAGE))) &&                       \
-         !((__vma)->vm_flags & VM_NOHUGEPAGE))
+         !((__vma)->vm_flags & VM_NOHUGEPAGE) &&                        \
+         !is_vma_temporary_stack(__vma))
 #define transparent_hugepage_defrag(__vma)                              \
         ((transparent_hugepage_flags &                                  \
           (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) ||                     \