[Devel] [PATCH RHEL8 COMMIT] ms/mm: vmscan: naming fixes: global_reclaim() and sane_reclaim()
Konstantin Khorenko
khorenko at virtuozzo.com
Thu Apr 2 16:02:56 MSK 2020
The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.3.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.4
------>
commit 63c4eac1d8dcf6495b5fa4a1bd844b9d45e57eb6
Author: Johannes Weiner <hannes at cmpxchg.org>
Date: Thu Apr 2 16:02:55 2020 +0300
ms/mm: vmscan: naming fixes: global_reclaim() and sane_reclaim()
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. Use "writeback_throttling_sane()".
Link: http://lkml.kernel.org/r/20191022144803.302233-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes at cmpxchg.org>
Reviewed-by: Roman Gushchin <guro at fb.com>
Acked-by: Michal Hocko <mhocko at suse.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(cherry picked from commit b5ead35e7e1d3434ce436dfcb2af32820ce54589)
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
mm/vmscan.c | 46 ++++++++++++++++++++++------------------------
1 file changed, 22 insertions(+), 24 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7be29b8b4811..dbbef91f5d2b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -170,13 +170,13 @@ static LIST_HEAD(shrinker_list);
static DECLARE_RWSEM(shrinker_rwsem);
#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_throttling_sane - is the usual dirty throttling mechanism available?
* @sc: scan_control in question
*
* The normal page dirty throttling mechanism in balance_dirty_pages() is
@@ -188,11 +188,9 @@ 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_throttling_sane(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 (1/*cgroup_subsys_on_dfl(memory_cgrp_subsys)*/)
@@ -224,12 +222,12 @@ 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_throttling_sane(struct scan_control *sc)
{
return true;
}
@@ -1050,7 +1048,7 @@ 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_throttling_sane(sc) ||
!PageReclaim(page) || !may_enter_fs) {
/*
* This is slightly racy - end_page_writeback()
@@ -1620,7 +1618,7 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
if (current_is_kswapd())
return 0;
- if (!sane_reclaim(sc))
+ if (!writeback_throttling_sane(sc))
return 0;
if (file) {
@@ -1756,12 +1754,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
reclaim_stat->recent_scanned[file] += nr_taken;
if (current_is_kswapd()) {
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_vm_events(PGSCAN_KSWAPD, nr_scanned);
count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD,
nr_scanned);
} else {
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_vm_events(PGSCAN_DIRECT, nr_scanned);
count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT,
nr_scanned);
@@ -1777,12 +1775,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
spin_lock_irq(&pgdat->lru_lock);
if (current_is_kswapd()) {
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed);
count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD,
nr_reclaimed);
} else {
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
__count_vm_events(PGSTEAL_DIRECT, nr_reclaimed);
count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT,
nr_reclaimed);
@@ -2115,7 +2113,7 @@ 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;
}
@@ -2139,7 +2137,7 @@ 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;
@@ -2315,7 +2313,7 @@ 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);
@@ -2563,14 +2561,14 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
* retry with decreasing priority if one round over the
* whole hierarchy is not sufficient.
*/
- if (!global_reclaim(sc) &&
+ if (cgroup_reclaim(sc) &&
sc->nr_reclaimed >= sc->nr_to_reclaim) {
mem_cgroup_iter_break(root, memcg);
break;
}
} while ((memcg = mem_cgroup_iter(root, memcg, &reclaim)));
- if (global_reclaim(sc))
+ if (!cgroup_reclaim(sc))
shrink_slab(sc->gfp_mask, pgdat->node_id, NULL,
sc->priority, false);
@@ -2634,7 +2632,7 @@ 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_throttling_sane(sc) &&
sc->nr.dirty && sc->nr.dirty == sc->nr.congested)
set_memcg_congestion(pgdat, root, true);
@@ -2729,7 +2727,7 @@ 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;
@@ -2832,7 +2830,7 @@ 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 {
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