linux-kernel - [PATCH 1/9] mm: workingset: don't drop refault information prematurely

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180828172258.3185-2-hannes@cmpxchg.org>
Date:   Tue, 28 Aug 2018 13:22:50 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Tejun Heo <tj@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>,
        Daniel Drake <drake@...lessm.com>,
        Vinayak Menon <vinmenon@...eaurora.org>,
        Christopher Lameter <cl@...ux.com>,
        Peter Enderborg <peter.enderborg@...y.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Mike Galbraith <efault@....de>, linux-mm@...ck.org,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com
Subject: [PATCH 1/9] mm: workingset: don't drop refault information prematurely

From: Johannes Weiner <jweiner@...com>

If we keep just enough refault information to match the *current* page
cache during reclaim time, we could lose a lot of events when there is
only a temporary spike in non-cache memory consumption that pushes out
all the cache. Once cache comes back, we won't see those refaults.
They might not be actionable for LRU aging, but we want to know about
them for measuring memory pressure.

Signed-off-by: Johannes Weiner <jweiner@...com>
---
 mm/workingset.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/workingset.c b/mm/workingset.c
index 40ee02c83978..53759a3cf99a 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -364,7 +364,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 {
 	unsigned long max_nodes;
 	unsigned long nodes;
-	unsigned long cache;
+	unsigned long pages;
 
 	/* list_lru lock nests inside the IRQ-safe i_pages lock */
 	local_irq_disable();
@@ -393,14 +393,14 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	 *
 	 * PAGE_SIZE / radix_tree_nodes / node_entries * 8 / PAGE_SIZE
 	 */
-	if (sc->memcg) {
-		cache = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
-						     LRU_ALL_FILE);
-	} else {
-		cache = node_page_state(NODE_DATA(sc->nid), NR_ACTIVE_FILE) +
-			node_page_state(NODE_DATA(sc->nid), NR_INACTIVE_FILE);
-	}
-	max_nodes = cache >> (RADIX_TREE_MAP_SHIFT - 3);
+#ifdef CONFIG_MEMCG
+	if (sc->memcg)
+		pages = page_counter_read(&sc->memcg->memory);
+	else
+#endif
+		pages = node_present_pages(sc->nid);
+
+	max_nodes = pages >> (RADIX_TREE_MAP_SHIFT - 3);
 
 	if (nodes <= max_nodes)
 		return 0;
-- 
2.18.0