mm: introduce vma_is_anonymous(vma) helper
special_mapping_fault() is absolutely broken. It seems it was always
wrong, but this didn't matter until vdso/vvar started to use more than
one page.
And after this change vma_is_anonymous() becomes really trivial, it
simply checks vm_ops == NULL. However, I do think the helper makes
sense. There are a lot of ->vm_ops != NULL checks, the helper makes the
caller's code more understandable (self-documented) and this is more
grep-friendly.
This patch (of 3):
Preparation. Add the new simple helper, vma_is_anonymous(vma), and change
handle_pte_fault() to use it. It will have more users.
The name is not accurate, say a hpet_mmap()'ed vma is not anonymous.
Perhaps it should be named vma_has_fault() instead. But it matches the
logic in mmap.c/memory.c (see next changes). "True" just means that a
page fault will use do_anonymous_page().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index bb04d8f..882c9d7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3267,12 +3267,12 @@
barrier();
if (!pte_present(entry)) {
if (pte_none(entry)) {
- if (vma->vm_ops)
+ if (vma_is_anonymous(vma))
+ return do_anonymous_page(mm, vma, address,
+ pte, pmd, flags);
+ else
return do_fault(mm, vma, address, pte, pmd,
flags, entry);
-
- return do_anonymous_page(mm, vma, address, pte, pmd,
- flags);
}
return do_swap_page(mm, vma, address,
pte, pmd, flags, entry);