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authorYang Shi <shy828301@gmail.com>2021-05-04 18:36:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 11:27:23 -0700
commit41ca668a71e7b03743369a2c6d8b8edc1e943dc8 (patch)
tree53630cc82f1c6e1fa2294e1d99a2c7f32120ee4a /mm/vmscan.c
parent468ab8437a97a953895856c3709e48b3067da13c (diff)
mm: vmscan: use a new flag to indicate shrinker is registered
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. Remove SHRINKER_REGISTERING since we could check if shrinker is registered successfully by the new flag. Link: https://lkml.kernel.org/r/20210311190845.9708-9-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c40
1 files changed, 15 insertions, 25 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 400f4a657b27..d1601163d895 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -316,19 +316,6 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
}
}
-/*
- * We allow subsystems to populate their shrinker-related
- * LRU lists before register_shrinker_prepared() is called
- * for the shrinker, since we don't want to impose
- * restrictions on their internal registration order.
- * In this case shrink_slab_memcg() may find corresponding
- * bit is set in the shrinkers map.
- *
- * This value is used by the function to detect registering
- * shrinkers and to skip do_shrink_slab() calls for them.
- */
-#define SHRINKER_REGISTERING ((struct shrinker *)~0UL)
-
static DEFINE_IDR(shrinker_idr);
static int prealloc_memcg_shrinker(struct shrinker *shrinker)
@@ -337,7 +324,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
down_write(&shrinker_rwsem);
/* This may call shrinker, so it must use down_read_trylock() */
- id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL);
+ id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
if (id < 0)
goto unlock;
@@ -360,9 +347,9 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
BUG_ON(id < 0);
- down_write(&shrinker_rwsem);
+ lockdep_assert_held(&shrinker_rwsem);
+
idr_remove(&shrinker_idr, id);
- up_write(&shrinker_rwsem);
}
static bool cgroup_reclaim(struct scan_control *sc)
@@ -490,8 +477,11 @@ void free_prealloced_shrinker(struct shrinker *shrinker)
if (!shrinker->nr_deferred)
return;
- if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+ if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
+ down_write(&shrinker_rwsem);
unregister_memcg_shrinker(shrinker);
+ up_write(&shrinker_rwsem);
+ }
kfree(shrinker->nr_deferred);
shrinker->nr_deferred = NULL;
@@ -501,10 +491,7 @@ void register_shrinker_prepared(struct shrinker *shrinker)
{
down_write(&shrinker_rwsem);
list_add_tail(&shrinker->list, &shrinker_list);
-#ifdef CONFIG_MEMCG
- if (shrinker->flags & SHRINKER_MEMCG_AWARE)
- idr_replace(&shrinker_idr, shrinker, shrinker->id);
-#endif
+ shrinker->flags |= SHRINKER_REGISTERED;
up_write(&shrinker_rwsem);
}
@@ -524,13 +511,16 @@ EXPORT_SYMBOL(register_shrinker);
*/
void unregister_shrinker(struct shrinker *shrinker)
{
- if (!shrinker->nr_deferred)
+ if (!(shrinker->flags & SHRINKER_REGISTERED))
return;
- if (shrinker->flags & SHRINKER_MEMCG_AWARE)
- unregister_memcg_shrinker(shrinker);
+
down_write(&shrinker_rwsem);
list_del(&shrinker->list);
+ shrinker->flags &= ~SHRINKER_REGISTERED;
+ if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+ unregister_memcg_shrinker(shrinker);
up_write(&shrinker_rwsem);
+
kfree(shrinker->nr_deferred);
shrinker->nr_deferred = NULL;
}
@@ -695,7 +685,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
struct shrinker *shrinker;
shrinker = idr_find(&shrinker_idr, i);
- if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) {
+ if (unlikely(!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))) {
if (!shrinker)
clear_bit(i, info->map);
continue;