userfaultfd: report UFFDIO_ZEROPAGE as available for shmem VMAs

Now when shmem VMAs can be filled with zero page via userfaultfd we can
report that UFFDIO_ZEROPAGE is available for those VMAs

Link: http://lkml.kernel.org/r/1497939652-16528-7-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 886085b47c75e6914cb1084cb4e8ec681af92945..01a85e2660b8d4598e539fd454cb7d7ec67fa039 100644 (file)
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1194,7 +1194,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
        struct uffdio_register __user *user_uffdio_register;
        unsigned long vm_flags, new_flags;
        bool found;
-       bool non_anon_pages;
+       bool basic_ioctls;
        unsigned long start, end, vma_end;
 
        user_uffdio_register = (struct uffdio_register __user *) arg;
@@ -1260,7 +1260,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
         * Search for not compatible vmas.
         */
        found = false;
-       non_anon_pages = false;
+       basic_ioctls = false;
        for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
                cond_resched();
 
@@ -1299,8 +1299,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
                /*
                 * Note vmas containing huge pages
                 */
-               if (is_vm_hugetlb_page(cur) || vma_is_shmem(cur))
-                       non_anon_pages = true;
+               if (is_vm_hugetlb_page(cur))
+                       basic_ioctls = true;
 
                found = true;
        }
@@ -1371,7 +1371,7 @@ out_unlock:
                 * userland which ioctls methods are guaranteed to
                 * succeed on this range.
                 */
-               if (put_user(non_anon_pages ? UFFD_API_RANGE_IOCTLS_BASIC :
+               if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC :
                             UFFD_API_RANGE_IOCTLS,
                             &user_uffdio_register->ioctls))
                        ret = -EFAULT;