mm: move swap-in anonymous page into active list

Every swap-in anonymous page starts from inactive lru list's head.  It
should be activated unconditionally when VM decide to reclaim because
page table entry for the page always usually has marked accessed bit.
Thus, their window size for getting a new referece is 2 * NR_inactive +
NR_active while others is NR_inactive + NR_active.

It's not fair that it has more chance to be referenced compared to other
newly allocated page which starts from active lru list's head.

Johannes:

: The page can still have a valid copy on the swap device, so prefering to
: reclaim that page over a fresh one could make sense.  But as you point
: out, having it start inactive instead of active actually ends up giving it
: *more* LRU time, and that seems to be without justification.

Rik:

: The reason newly read in swap cache pages start on the inactive list is
: that we do some amount of read-around, and do not know which pages will
: get used.
:
: However, immediately activating the ones that DO get used, like your patch
: does, is the right thing to do.

Link: http://lkml.kernel.org/r/1469762740-17860-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
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 04004834e985fcd95b6b468976359ea1de21ed01..83be99d9d8a15006e2cb267a3dd46e10e470f66e 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2642,6 +2642,7 @@ int do_swap_page(struct fault_env *fe, pte_t orig_pte)
        if (page == swapcache) {
                do_page_add_anon_rmap(page, vma, fe->address, exclusive);
                mem_cgroup_commit_charge(page, memcg, true, false);
+               activate_page(page);
        } else { /* ksm created a completely new copy */
                page_add_new_anon_rmap(page, vma, fe->address, false);
                mem_cgroup_commit_charge(page, memcg, false, false);