[v3 PATCH 05/11] mm: vmscan: use a new flag to indicate shrinker is registered
From: Yang Shi <hidden>
Date: 2021-01-05 23:00:13
Also in:
linux-fsdevel, lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - reclaim, shrinker, the rest · Maintainers:
Andrew Morton, Johannes Weiner, Dave Chinner, Linus Torvalds
Currently registered shrinker is indicated by non-NULL shrinker->nr_deferred. This approach is fine with nr_deferred at the shrinker level, but the following patches will move MEMCG_AWARE shrinkers' nr_deferred to memcg level, so their shrinker->nr_deferred would always be NULL. This would prevent the shrinkers from unregistering correctly. Signed-off-by: Yang Shi <redacted> --- include/linux/shrinker.h | 7 ++++--- mm/vmscan.c | 13 +++++++++---- 2 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 0f80123650e2..1eac79ce57d4 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h@@ -79,13 +79,14 @@ struct shrinker { #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ /* Flags */ -#define SHRINKER_NUMA_AWARE (1 << 0) -#define SHRINKER_MEMCG_AWARE (1 << 1) +#define SHRINKER_REGISTERED (1 << 0) +#define SHRINKER_NUMA_AWARE (1 << 1) +#define SHRINKER_MEMCG_AWARE (1 << 2) /* * It just makes sense when the shrinker is also MEMCG_AWARE for now, * non-MEMCG_AWARE shrinker should not have this flag set. */ -#define SHRINKER_NONSLAB (1 << 2) +#define SHRINKER_NONSLAB (1 << 3) extern int prealloc_shrinker(struct shrinker *shrinker); extern void register_shrinker_prepared(struct shrinker *shrinker);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8da765a85569..9761c7c27412 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -494,6 +494,7 @@ void register_shrinker_prepared(struct shrinker *shrinker) if (shrinker->flags & SHRINKER_MEMCG_AWARE) idr_replace(&shrinker_idr, shrinker, shrinker->id); #endif + shrinker->flags |= SHRINKER_REGISTERED; up_write(&shrinker_rwsem); }
@@ -513,13 +514,17 @@ EXPORT_SYMBOL(register_shrinker); */ void unregister_shrinker(struct shrinker *shrinker) { - if (!shrinker->nr_deferred) - return; - if (shrinker->flags & SHRINKER_MEMCG_AWARE) - unregister_memcg_shrinker(shrinker); down_write(&shrinker_rwsem); + if (!(shrinker->flags & SHRINKER_REGISTERED)) { + up_write(&shrinker_rwsem); + return; + } list_del(&shrinker->list); + shrinker->flags &= ~SHRINKER_REGISTERED; up_write(&shrinker_rwsem); + + if (shrinker->flags & SHRINKER_MEMCG_AWARE) + unregister_memcg_shrinker(shrinker); kfree(shrinker->nr_deferred); shrinker->nr_deferred = NULL; }
--
2.26.2