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 <[email protected]> > Reviewed-by: Kirill Tkhai <[email protected]> > Signed-off-by: Yang Shi <[email protected]>
Acked-by: Roman Gushchin <[email protected]> Thanks! > --- > 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 >
