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mm: vmscan: naming fixes: global_reclaim() and sane_reclaim()

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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@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2019-11-30 17:55:40 -08:00 committed by Linus Torvalds
parent a108629149
commit b5ead35e7e
1 changed files with 18 additions and 20 deletions
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38
mm/vmscan.c
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@ -239,13 +239,13 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
up_write(&shrinker_rwsem);
}
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
@ -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_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 (cgroup_subsys_on_dfl(memory_cgrp_subsys))
@ -302,12 +300,12 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
{
}
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;
}
@ -1227,7 +1225,7 @@ 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()
@ -1821,7 +1819,7 @@ 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) {
@ -1971,7 +1969,7 @@ 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);
@ -1985,7 +1983,7 @@ 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];
@ -2309,7 +2307,7 @@ 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;
}
@ -2333,7 +2331,7 @@ 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;
@ -2564,7 +2562,7 @@ 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);
@ -2853,7 +2851,7 @@ 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);
@ -2948,7 +2946,7 @@ 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;
@ -3048,7 +3046,7 @@ 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 {