Re: [v3 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map_size
From: Kirill Tkhai <hidden>
Date: 2021-01-06 10:17:07
Also in:
linux-fsdevel, lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - reclaim, the rest · Maintainers:
Andrew Morton, Johannes Weiner, Linus Torvalds
On 06.01.2021 01:58, Yang Shi wrote:
quoted hunk ↗ jump to hunk
Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both. Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the bit map. Signed-off-by: Yang Shi <redacted> --- mm/vmscan.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)diff --git a/mm/vmscan.c b/mm/vmscan.c index ddb9f972f856..8da765a85569 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c@@ -185,8 +185,7 @@ static LIST_HEAD(shrinker_list); static DECLARE_RWSEM(shrinker_rwsem); #ifdef CONFIG_MEMCG - -static int memcg_shrinker_map_size; +static int shrinker_nr_max; static void memcg_free_shrinker_map_rcu(struct rcu_head *head) {@@ -248,7 +247,7 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) return 0; down_read(&shrinker_rwsem); - size = memcg_shrinker_map_size; + size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); for_each_node(nid) { map = kvzalloc(sizeof(*map) + size, GFP_KERNEL); if (!map) {@@ -269,7 +268,7 @@ static int memcg_expand_shrinker_maps(int new_id) struct mem_cgroup *memcg; size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long); - old_size = memcg_shrinker_map_size; + old_size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); if (size <= old_size) return 0;
These bunch of DIV_ROUND_UP() looks too complex. Since now all the shrinker maps allocation logic in the only file, can't we simplify this to look better? I mean something like below to merge in your patch:
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b951c289ef3a..27b6371a1656 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -247,7 +247,7 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) return 0; down_read(&shrinker_rwsem); - size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); + size = shrinker_nr_max / BITS_PER_BYTE; for_each_node(nid) { map = kvzalloc(sizeof(*map) + size, GFP_KERNEL); if (!map) {
@@ -264,13 +264,11 @@ int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg) static int memcg_expand_shrinker_maps(int new_id) { - int size, old_size, ret = 0; + int size, old_size, new_nr_max, ret = 0; struct mem_cgroup *memcg; size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long); - old_size = DIV_ROUND_UP(shrinker_nr_max, BITS_PER_LONG) * sizeof(unsigned long); - if (size <= old_size) - return 0; + new_nr_max = size * BITS_PER_BYTE; if (!root_mem_cgroup) goto out;
@@ -287,6 +285,9 @@ static int memcg_expand_shrinker_maps(int new_id) } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); out: + if (ret == 0) + shrinker_nr_max = new_nr_max; + return ret; }
@@ -334,8 +335,6 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) idr_remove(&shrinker_idr, id); goto unlock; } - - shrinker_nr_max = id + 1; } shrinker->id = id; ret = 0;