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mm: memcg: rename and document global_reclaim() 

Evidently, global_reclaim() can be a confusing name.  Especially that it
used to exist before with a subtly different definition (removed by commit
b5ead35e7e ("mm: vmscan: naming fixes: global_reclaim() and
sane_reclaim()").  It can be interpreted as non-cgroup reclaim, even
though it returns true for cgroup reclaim on the root memcg (through
memory.reclaim).

Rename it to root_reclaim() in an attempt to make it less ambiguous, and
add documentation to it as well as cgroup_reclaim.

Link: https://lkml.kernel.org/r/20230621023053.432374-1-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Closes: https://lore.kernel.org/lkml/20230405200150.GA35884@cmpxchg.org/
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yosry Ahmed 2023-06-21 02:30:53 +00:00 committed by Andrew Morton
parent 7302338a14
commit 7a704474b3
1 changed files with 13 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
mm/vmscan.c
View File

@ -429,12 +429,17 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg)
up_read(&shrinker_rwsem);
}
/* Returns true for reclaim through cgroup limits or cgroup interfaces. */
static bool cgroup_reclaim(struct scan_control *sc)
{
return sc->target_mem_cgroup;
}
static bool global_reclaim(struct scan_control *sc)
/*
* Returns true for reclaim on the root cgroup. This is true for direct
* allocator reclaim and reclaim through cgroup interfaces on the root cgroup.
*/
static bool root_reclaim(struct scan_control *sc)
{
return !sc->target_mem_cgroup || mem_cgroup_is_root(sc->target_mem_cgroup);
}
@ -489,7 +494,7 @@ static bool cgroup_reclaim(struct scan_control *sc)
return false;
}
static bool global_reclaim(struct scan_control *sc)
static bool root_reclaim(struct scan_control *sc)
{
return true;
}
@ -546,7 +551,7 @@ static void flush_reclaim_state(struct scan_control *sc)
* memcg reclaim, to make reporting more accurate and reduce
* underestimation, but it's probably not worth the complexity for now.
*/
if (current->reclaim_state && global_reclaim(sc)) {
if (current->reclaim_state && root_reclaim(sc)) {
sc->nr_reclaimed += current->reclaim_state->reclaimed;
current->reclaim_state->reclaimed = 0;
}
@ -5325,7 +5330,7 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool
static unsigned long get_nr_to_reclaim(struct scan_control *sc)
{
/* don't abort memcg reclaim to ensure fairness */
if (!global_reclaim(sc))
if (!root_reclaim(sc))
return -1;
return max(sc->nr_to_reclaim, compact_gap(sc->order));
@ -5477,7 +5482,7 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc
{
struct blk_plug plug;
VM_WARN_ON_ONCE(global_reclaim(sc));
VM_WARN_ON_ONCE(root_reclaim(sc));
VM_WARN_ON_ONCE(!sc->may_writepage || !sc->may_unmap);
lru_add_drain();
@ -5538,7 +5543,7 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *
struct blk_plug plug;
unsigned long reclaimed = sc->nr_reclaimed;
VM_WARN_ON_ONCE(!global_reclaim(sc));
VM_WARN_ON_ONCE(!root_reclaim(sc));
/*
* Unmapped clean folios are already prioritized. Scanning for more of
@ -6260,7 +6265,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
bool proportional_reclaim;
struct blk_plug plug;
if (lru_gen_enabled() && !global_reclaim(sc)) {
if (lru_gen_enabled() && !root_reclaim(sc)) {
lru_gen_shrink_lruvec(lruvec, sc);
return;
}
@ -6501,7 +6506,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
struct lruvec *target_lruvec;
bool reclaimable = false;
if (lru_gen_enabled() && global_reclaim(sc)) {
if (lru_gen_enabled() && root_reclaim(sc)) {
lru_gen_shrink_node(pgdat, sc);
return;
}