mlock: do not munlock pages in __do_fault()

If the page is going to be written to, __do_page needs to break COW.

However, the old page (before breaking COW) was never mapped mapped into
the current pte (__do_fault is only called when the pte is not present),
so vmscan can't have marked the old page as PageMlocked due to being
mapped in __do_fault's VMA.  Therefore, __do_fault() does not need to
worry about clearing PageMlocked() on the old page.

Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 6 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 32df03cf13a..8e8c1832486 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3051,12 +3051,6 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                                 goto out;
                         }
                         charged = 1;
-                        /*
-                         * Don't let another task, with possibly unlocked vma,
-                         * keep the mlocked page.
-                         */
-                        if (vma->vm_flags & VM_LOCKED)
-                                clear_page_mlock(vmf.page);
                         copy_user_highpage(page, vmf.page, address, vma);
                         __SetPageUptodate(page);
                 } else {