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Subject[patch 07/11] mm: vmscan: convert unevictable page rescue scanner to per-memcg LRU lists
Date
The global per-zone LRU lists are about to go away on memcg-enabled
kernels, the unevictable page rescue scanner must be able to find its
pages on the per-memcg LRU lists.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
---
include/linux/memcontrol.h | 3 ++
mm/memcontrol.c | 11 ++++++++
mm/vmscan.c | 61 ++++++++++++++++++++++++++++---------------
3 files changed, 54 insertions(+), 21 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 6575931..7795b72 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -40,6 +40,9 @@ extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
struct mem_cgroup *mem_cont,
int active, int file);

+struct page *mem_cgroup_lru_to_page(struct zone *, struct mem_cgroup *,
+ enum lru_list);
+
struct mem_cgroup_iter {
struct zone *zone;
int priority;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 518f640..27d78dc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -937,6 +937,17 @@ EXPORT_SYMBOL(mem_cgroup_count_vm_event);
* When moving account, the page is not on LRU. It's isolated.
*/

+struct page *mem_cgroup_lru_to_page(struct zone *zone, struct mem_cgroup *mem,
+ enum lru_list lru)
+{
+ struct mem_cgroup_per_zone *mz;
+ struct page_cgroup *pc;
+
+ mz = mem_cgroup_zoneinfo(mem, zone_to_nid(zone), zone_idx(zone));
+ pc = list_entry(mz->lists[lru].prev, struct page_cgroup, lru);
+ return lookup_cgroup_page(pc);
+}
+
void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
{
struct page_cgroup *pc;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8419e8f..bb4d8b8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3477,6 +3477,17 @@ void scan_mapping_unevictable_pages(struct address_space *mapping)

}

+/*
+ * XXX: Temporary helper to get to the last page of a mem_cgroup_zone
+ * lru list. This will be reasonably unified in a second.
+ */
+static struct page *lru_tailpage(struct mem_cgroup_zone *mz, enum lru_list lru)
+{
+ if (!scanning_global_lru(mz))
+ return mem_cgroup_lru_to_page(mz->zone, mz->mem_cgroup, lru);
+ return lru_to_page(&mz->zone->lru[lru].list);
+}
+
/**
* scan_zone_unevictable_pages - check unevictable list for evictable pages
* @zone - zone of which to scan the unevictable list
@@ -3490,32 +3501,40 @@ void scan_mapping_unevictable_pages(struct address_space *mapping)
#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
static void scan_zone_unevictable_pages(struct zone *zone)
{
- struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
- unsigned long scan;
- unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
-
- while (nr_to_scan > 0) {
- unsigned long batch_size = min(nr_to_scan,
- SCAN_UNEVICTABLE_BATCH_SIZE);
-
- spin_lock_irq(&zone->lru_lock);
- for (scan = 0; scan < batch_size; scan++) {
- struct page *page = lru_to_page(l_unevictable);
+ struct mem_cgroup *mem;

- if (!trylock_page(page))
- continue;
+ mem = mem_cgroup_iter(NULL, NULL, NULL);
+ do {
+ struct mem_cgroup_zone mz = {
+ .mem_cgroup = mem,
+ .zone = zone,
+ };
+ unsigned long nr_to_scan;

- prefetchw_prev_lru_page(page, l_unevictable, flags);
+ nr_to_scan = zone_nr_lru_pages(&mz, LRU_UNEVICTABLE);
+ while (nr_to_scan > 0) {
+ unsigned long batch_size;
+ unsigned long scan;

- if (likely(PageLRU(page) && PageUnevictable(page)))
- check_move_unevictable_page(page, zone);
+ batch_size = min(nr_to_scan,
+ SCAN_UNEVICTABLE_BATCH_SIZE);
+ spin_lock_irq(&zone->lru_lock);
+ for (scan = 0; scan < batch_size; scan++) {
+ struct page *page;

- unlock_page(page);
+ page = lru_tailpage(&mz, LRU_UNEVICTABLE);
+ if (!trylock_page(page))
+ continue;
+ if (likely(PageLRU(page) &&
+ PageUnevictable(page)))
+ check_move_unevictable_page(page, zone);
+ unlock_page(page);
+ }
+ spin_unlock_irq(&zone->lru_lock);
+ nr_to_scan -= batch_size;
}
- spin_unlock_irq(&zone->lru_lock);
-
- nr_to_scan -= batch_size;
- }
+ mem = mem_cgroup_iter(NULL, mem, NULL);
+ } while (mem);
}


--
1.7.6


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