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mm/vmscan: Consider anonymous pages without swap 

Reclaim anonymous pages if a migration path is available now that demotion
provides a non-swap recourse for reclaiming anon pages.

Note that this check is subtly different from the can_age_anon_pages()
checks.  This mechanism checks whether a specific page in a specific
context can actually be reclaimed, given current swap space and cgroup
limits.

can_age_anon_pages() is a much simpler and more preliminary check which
just says whether there is a possibility of future reclaim.

[kbusch@kernel.org: v11]
  Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
  Link: https://lkml.kernel.org/r/20210721063926.3024591-7-ying.huang@intel.com

Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Keith Busch 2021-09-02 14:59:26 -07:00 committed by Linus Torvalds
parent 2f368a9fb7
commit a2a36488a6
1 changed files with 30 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
mm/vmscan.c
View File

@ -524,7 +524,7 @@ static long add_nr_deferred(long nr, struct shrinker *shrinker,
static bool can_demote(int nid, struct scan_control *sc)
{
if (sc->no_demotion)
if (sc && sc->no_demotion)
return false;
if (next_demotion_node(nid) == NUMA_NO_NODE)
return false;
@ -533,6 +533,31 @@ static bool can_demote(int nid, struct scan_control *sc)
return false;
}
static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg,
int nid,
struct scan_control *sc)
{
if (memcg == NULL) {
/*
* For non-memcg reclaim, is there
* space in any swap device?
*/
if (get_nr_swap_pages() > 0)
return true;
} else {
/* Is the memcg below its swap limit? */
if (mem_cgroup_get_nr_swap_pages(memcg) > 0)
return true;
}
/*
* The page can not be swapped.
*
* Can it be reclaimed from this node via demotion?
*/
return can_demote(nid, sc);
}
/*
* This misses isolated pages which are not accounted for to save counters.
* As the data only determines if reclaim or compaction continues, it is
@ -544,7 +569,7 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +
zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);
if (get_nr_swap_pages() > 0)
if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL))
nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +
zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
@ -2541,6 +2566,7 @@ enum scan_balance {
static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
unsigned long *nr)
{
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
unsigned long anon_cost, file_cost, total_cost;
int swappiness = mem_cgroup_swappiness(memcg);
@ -2551,7 +2577,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
enum lru_list lru;
/* If we have no swap space, do not bother scanning anon pages. */
if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {
if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) {
scan_balance = SCAN_FILE;
goto out;
}
@ -2929,7 +2955,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat,
*/
pages_for_compaction = compact_gap(sc->order);
inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);
if (get_nr_swap_pages() > 0)
if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))
inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);
return inactive_lru_pages > pages_for_compaction;