Seven years after introducing the global_reclaim() function, I still
have to double take when reading a callsite. I don't know how others
do it. This is a terrible name.
Invert the meaning and rename it to cgroup_reclaim().
[ After all, "global reclaim" is just regular reclaim invoked from the
page allocator. It's reclaim on behalf of a cgroup limit that is a
special case of reclaim, and should be explicit - not the reverse. ]
sane_reclaim() isn't very descriptive either: it tests whether we can
use the regular writeback throttling - available during regular page
reclaim or cgroup2 limit reclaim - or need to use the broken
wait_on_page_writeback() method. Rename it to writeback_working().
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
mm/vmscan.c | 38 ++++++++++++++++++--------------------
1 file changed, 18 insertions(+), 20 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 69c4c82a9b5a..afd5e2432a8e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -239,13 +239,13 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
#endif /* CONFIG_MEMCG_KMEM */
#ifdef CONFIG_MEMCG
-static bool global_reclaim(struct scan_control *sc)
+static bool cgroup_reclaim(struct scan_control *sc)
{
- return !sc->target_mem_cgroup;
+ return sc->target_mem_cgroup;
}
/**
- * sane_reclaim - is the usual dirty throttling mechanism operational?
+ * writeback_working - is the usual dirty throttling mechanism unavailable?
* @sc: scan_control in question
*
* The normal page dirty throttling mechanism in balance_dirty_pages() is
@@ -257,11 +257,9 @@ static bool global_reclaim(struct scan_control *sc)
* This function tests whether the vmscan currently in progress can assume
* that the normal dirty throttling mechanism is operational.
*/
-static bool sane_reclaim(struct scan_control *sc)
+static bool writeback_working(struct scan_control *sc)
{
- struct mem_cgroup *memcg = sc->target_mem_cgroup;
-
- if (!memcg)
+ if (!cgroup_reclaim(sc))
return true;
#ifdef CONFIG_CGROUP_WRITEBACK
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
@@ -293,12 +291,12 @@ static bool memcg_congested(pg_data_t *pgdat,
}
#else
-static bool global_reclaim(struct scan_control *sc)
+static bool cgroup_reclaim(struct scan_control *sc)
{
- return true;
+ return false;
}
-static bool sane_reclaim(struct scan_control *sc)
+static bool writeback_working(struct scan_control *sc)
{
return true;
}
@@ -1211,7 +1209,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
goto activate_locked;
/* Case 2 above */
- } else if (sane_reclaim(sc) ||
+ } else if (writeback_working(sc) ||
!PageReclaim(page) || !may_enter_fs) {
/*
* This is slightly racy - end_page_writeback()
@@ -1806,7 +1804,7 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
if (current_is_kswapd())
return 0;
- if (!sane_reclaim(sc))
+ if (!writeback_working(sc))
return 0;
if (file) {
@@ -1957,7 +1955,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
reclaim_stat->recent_scanned[file] += nr_taken;
item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT;
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_vm_events(item, nr_scanned);
__count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
spin_unlock_irq(&pgdat->lru_lock);
@@ -1971,7 +1969,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
spin_lock_irq(&pgdat->lru_lock);
item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT;
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_vm_events(item, nr_reclaimed);
__count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
reclaim_stat->recent_rotated[0] += stat.nr_activate[0];
@@ -2239,7 +2237,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
* using the memory controller's swap limit feature would be
* too expensive.
*/
- if (!global_reclaim(sc) && !swappiness) {
+ if (cgroup_reclaim(sc) && !swappiness) {
scan_balance = SCAN_FILE;
goto out;
}
@@ -2263,7 +2261,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
* thrashing file LRU becomes infinitely more attractive than
* anon pages. Try to detect this based on file LRU size.
*/
- if (global_reclaim(sc)) {
+ if (!cgroup_reclaim(sc)) {
unsigned long pgdatfile;
unsigned long pgdatfree;
int z;
@@ -2494,7 +2492,7 @@ static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memc
* abort proportional reclaim if either the file or anon lru has already
* dropped to zero at the first pass.
*/
- scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() &&
+ scan_adjusted = (!cgroup_reclaim(sc) && !current_is_kswapd() &&
sc->priority == DEF_PRIORITY);
blk_start_plug(&plug);
@@ -2816,7 +2814,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
* Legacy memcg will stall in page writeback so avoid forcibly
* stalling in wait_iff_congested().
*/
- if (!global_reclaim(sc) && sane_reclaim(sc) &&
+ if (cgroup_reclaim(sc) && writeback_working(sc) &&
sc->nr.dirty && sc->nr.dirty == sc->nr.congested)
set_memcg_congestion(pgdat, root, true);
@@ -2911,7 +2909,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
* Take care memory controller reclaiming has small influence
* to global LRU.
*/
- if (global_reclaim(sc)) {
+ if (!cgroup_reclaim(sc)) {
if (!cpuset_zone_allowed(zone,
GFP_KERNEL | __GFP_HARDWALL))
continue;
@@ -3011,7 +3009,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
retry:
delayacct_freepages_start();
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
do {
--
2.21.0
