diff options
| -rw-r--r-- | fs/btrfs/super.c | 10 | ||||
| -rw-r--r-- | include/linux/memcontrol.h | 21 | ||||
| -rw-r--r-- | mm/shmem.c | 10 |
3 files changed, 41 insertions, 0 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index a7d804219bec..cc4537435399 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -22,6 +22,7 @@ #include <linux/namei.h> #include <linux/miscdevice.h> #include <linux/magic.h> +#include <linux/memcontrol.h> #include <linux/slab.h> #include <linux/ratelimit.h> #include <linux/crc32c.h> @@ -2434,6 +2435,15 @@ static long btrfs_nr_cached_objects(struct super_block *sb, struct shrink_contro struct btrfs_fs_info *fs_info = btrfs_sb(sb); const s64 nr = percpu_counter_read_positive(&fs_info->evictable_extent_maps); + /* + * The evictable extent map counter is filesystem-global and does not + * honour sc->memcg, so it is only meaningful on the global (kswapd or + * root direct reclaim) shrink path. Skip the per-memcg iterations of + * shrink_slab_memcg() to avoid queueing duplicate global work. + */ + if (!mem_cgroup_shrink_is_root(sc)) + return 0; + trace_btrfs_extent_map_shrinker_count(fs_info, nr); return nr; diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index e1f46a0016fc..5407e4200460 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -520,6 +520,22 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) return (memcg == root_mem_cgroup); } +/** + * mem_cgroup_shrink_is_root - is this a global or root-memcg shrink invocation? + * @sc: shrink_control describing the current shrinker call + * + * Returns true when @sc represents a global reclaim shrink (sc->memcg == NULL) + * or a root-memcg shrink, i.e. not a per-memcg iteration of + * shrink_slab_memcg(). Filesystems whose ->nr_cached_objects()/ + * ->free_cached_objects() implementations operate on filesystem-global state + * and do not honour sc->memcg can use this to early-return 0 in per-memcg + * contexts. + */ +static inline bool mem_cgroup_shrink_is_root(struct shrink_control *sc) +{ + return !sc->memcg || mem_cgroup_is_root(sc->memcg); +} + static inline bool obj_cgroup_is_root(const struct obj_cgroup *objcg) { return objcg->is_root; @@ -1071,6 +1087,11 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) return true; } +static inline bool mem_cgroup_shrink_is_root(struct shrink_control *sc) +{ + return true; +} + static inline bool obj_cgroup_is_root(const struct obj_cgroup *objcg) { return true; diff --git a/mm/shmem.c b/mm/shmem.c index b51f83c970bb..9001aaf3b7b9 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -846,6 +846,16 @@ static long shmem_unused_huge_count(struct super_block *sb, struct shrink_control *sc) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); + + /* + * The per-superblock shrinklist is filesystem-global and does not + * honour sc->memcg, so it is only meaningful on the global (kswapd or + * root direct reclaim) shrink path. Skip the per-memcg iterations of + * shrink_slab_memcg() to avoid queueing duplicate global work. + */ + if (!mem_cgroup_shrink_is_root(sc)) + return 0; + return READ_ONCE(sbinfo->shrinklist_len); } #else /* !CONFIG_TRANSPARENT_HUGEPAGE */ |