mm: don't waste swap on locked pages
try_to_unmap always fails on a page found in a VM_LOCKED vma (unless
migrating), and recycles it back to the active list. But if it's an
anonymous page, we've already allocated swap to it: just wasting swap.
Spot locked pages in page_referenced_one and treat them as referenced.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ethan Solomita <solo@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/rmap.c b/mm/rmap.c
index 0334c8f..57ad276 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -283,7 +283,10 @@
if (!pte)
goto out;
- if (ptep_clear_flush_young(vma, address, pte))
+ if (vma->vm_flags & VM_LOCKED) {
+ referenced++;
+ *mapcount = 1; /* break early from loop */
+ } else if (ptep_clear_flush_young(vma, address, pte))
referenced++;
/* Pretend the page is referenced if the task has the
