Re: [v7 PATCH 10/12] mm: vmscan: don't need allocate shrinker->nr_deferred for memcg aware shrinkers
From: Roman Gushchin <hidden>
Date: 2021-02-10 01:26:08
Also in:
linux-mm, lkml
On Tue, Feb 09, 2021 at 09:46:44AM -0800, Yang Shi wrote:
Now nr_deferred is available on per memcg level for memcg aware shrinkers, so don't need allocate shrinker->nr_deferred for such shrinkers anymore. The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or memcg is disabled by kernel command line, then shrinker's SHRINKER_MEMCG_AWARE flag would be cleared. This makes the implementation of this patch simpler. Acked-by: Vlastimil Babka <redacted> Reviewed-by: Kirill Tkhai <redacted> Signed-off-by: Yang Shi <redacted>
Acked-by: Roman Gushchin <redacted> Thanks!
quoted hunk ↗ jump to hunk
--- mm/vmscan.c | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-)diff --git a/mm/vmscan.c b/mm/vmscan.c index 748aa6e90f83..dfde6e7fd7f5 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c@@ -338,6 +338,9 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) { int id, ret = -ENOMEM; + if (mem_cgroup_disabled()) + return -ENOSYS; + down_write(&shrinker_rwsem); /* This may call shrinker, so it must use down_read_trylock() */ id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);@@ -417,7 +420,7 @@ static bool writeback_throttling_sane(struct scan_control *sc) #else static int prealloc_memcg_shrinker(struct shrinker *shrinker) { - return 0; + return -ENOSYS; } static void unregister_memcg_shrinker(struct shrinker *shrinker)@@ -528,8 +531,18 @@ unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone */ int prealloc_shrinker(struct shrinker *shrinker) { - unsigned int size = sizeof(*shrinker->nr_deferred); + unsigned int size; + int err; + if (shrinker->flags & SHRINKER_MEMCG_AWARE) { + err = prealloc_memcg_shrinker(shrinker); + if (err != -ENOSYS) + return err; + + shrinker->flags &= ~SHRINKER_MEMCG_AWARE; + } + + size = sizeof(*shrinker->nr_deferred); if (shrinker->flags & SHRINKER_NUMA_AWARE) size *= nr_node_ids;@@ -537,26 +550,16 @@ int prealloc_shrinker(struct shrinker *shrinker) if (!shrinker->nr_deferred) return -ENOMEM; - if (shrinker->flags & SHRINKER_MEMCG_AWARE) { - if (prealloc_memcg_shrinker(shrinker)) - goto free_deferred; - } return 0; - -free_deferred: - kfree(shrinker->nr_deferred); - shrinker->nr_deferred = NULL; - return -ENOMEM; } void free_prealloced_shrinker(struct shrinker *shrinker) { - if (!shrinker->nr_deferred) - return; - - if (shrinker->flags & SHRINKER_MEMCG_AWARE) + if (shrinker->flags & SHRINKER_MEMCG_AWARE) { unregister_memcg_shrinker(shrinker); + return; + } kfree(shrinker->nr_deferred); shrinker->nr_deferred = NULL;-- 2.26.2