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-rw-r--r--mm/vmscan.c86
1 files changed, 72 insertions, 14 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index e5d52d6a24af..ee4eecc7e1c2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -351,12 +351,13 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
*/
unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
{
- unsigned long lru_size;
+ unsigned long lru_size = 0;
int zid;
- if (!mem_cgroup_disabled())
- lru_size = lruvec_page_state_local(lruvec, NR_LRU_BASE + lru);
- else
+ if (!mem_cgroup_disabled()) {
+ for (zid = 0; zid < MAX_NR_ZONES; zid++)
+ lru_size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
+ } else
lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
@@ -932,10 +933,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
* Note that if SetPageDirty is always performed via set_page_dirty,
* and thus under the i_pages lock, then this ordering is not required.
*/
- if (unlikely(PageTransHuge(page)) && PageSwapCache(page))
- refcount = 1 + HPAGE_PMD_NR;
- else
- refcount = 2;
+ refcount = 1 + compound_nr(page);
if (!page_ref_freeze(page, refcount))
goto cannot_free;
/* note: atomic_cmpxchg in page_ref_freeze provides the smp_rmb */
@@ -2459,17 +2457,70 @@ out:
*lru_pages = 0;
for_each_evictable_lru(lru) {
int file = is_file_lru(lru);
- unsigned long size;
+ unsigned long lruvec_size;
unsigned long scan;
+ unsigned long protection;
+
+ lruvec_size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
+ protection = mem_cgroup_protection(memcg,
+ sc->memcg_low_reclaim);
+
+ if (protection) {
+ /*
+ * Scale a cgroup's reclaim pressure by proportioning
+ * its current usage to its memory.low or memory.min
+ * setting.
+ *
+ * This is important, as otherwise scanning aggression
+ * becomes extremely binary -- from nothing as we
+ * approach the memory protection threshold, to totally
+ * nominal as we exceed it. This results in requiring
+ * setting extremely liberal protection thresholds. It
+ * also means we simply get no protection at all if we
+ * set it too low, which is not ideal.
+ *
+ * If there is any protection in place, we reduce scan
+ * pressure by how much of the total memory used is
+ * within protection thresholds.
+ *
+ * There is one special case: in the first reclaim pass,
+ * we skip over all groups that are within their low
+ * protection. If that fails to reclaim enough pages to
+ * satisfy the reclaim goal, we come back and override
+ * the best-effort low protection. However, we still
+ * ideally want to honor how well-behaved groups are in
+ * that case instead of simply punishing them all
+ * equally. As such, we reclaim them based on how much
+ * memory they are using, reducing the scan pressure
+ * again by how much of the total memory used is under
+ * hard protection.
+ */
+ unsigned long cgroup_size = mem_cgroup_size(memcg);
+
+ /* Avoid TOCTOU with earlier protection check */
+ cgroup_size = max(cgroup_size, protection);
+
+ scan = lruvec_size - lruvec_size * protection /
+ cgroup_size;
+
+ /*
+ * Minimally target SWAP_CLUSTER_MAX pages to keep
+ * reclaim moving forwards, avoiding decremeting
+ * sc->priority further than desirable.
+ */
+ scan = max(scan, SWAP_CLUSTER_MAX);
+ } else {
+ scan = lruvec_size;
+ }
+
+ scan >>= sc->priority;
- size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
- scan = size >> sc->priority;
/*
* If the cgroup's already been deleted, make sure to
* scrape out the remaining cache.
*/
if (!scan && !mem_cgroup_online(memcg))
- scan = min(size, SWAP_CLUSTER_MAX);
+ scan = min(lruvec_size, SWAP_CLUSTER_MAX);
switch (scan_balance) {
case SCAN_EQUAL:
@@ -2489,7 +2540,7 @@ out:
case SCAN_ANON:
/* Scan one type exclusively */
if ((scan_balance == SCAN_FILE) != file) {
- size = 0;
+ lruvec_size = 0;
scan = 0;
}
break;
@@ -2498,7 +2549,7 @@ out:
BUG();
}
- *lru_pages += size;
+ *lru_pages += lruvec_size;
nr[lru] = scan;
}
}
@@ -2742,6 +2793,13 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
memcg_memory_event(memcg, MEMCG_LOW);
break;
case MEMCG_PROT_NONE:
+ /*
+ * All protection thresholds breached. We may
+ * still choose to vary the scan pressure
+ * applied based on by how much the cgroup in
+ * question has exceeded its protection
+ * thresholds (see get_scan_count).
+ */
break;
}