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[73.93.239.127]) by smtp.gmail.com with ESMTPSA id y12sm99220pjc.56.2021.02.16.16.13.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Feb 2021 16:13:46 -0800 (PST) From: Yang Shi To: guro@fb.com, ktkhai@virtuozzo.com, vbabka@suse.cz, shakeelb@google.com, david@fromorbit.com, hannes@cmpxchg.org, mhocko@suse.com, akpm@linux-foundation.org Cc: shy828301@gmail.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [v8 PATCH 08/13] mm: vmscan: use a new flag to indicate shrinker is registered Date: Tue, 16 Feb 2021 16:13:17 -0800 Message-Id: <20210217001322.2226796-9-shy828301@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210217001322.2226796-1-shy828301@gmail.com> References: <20210217001322.2226796-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Acked-by: Kirill Tkhai Acked-by: Vlastimil Babka Signed-off-by: Yang Shi --- include/linux/shrinker.h | 7 ++++--- mm/vmscan.c | 40 +++++++++++++++------------------------- 2 files changed, 19 insertions(+), 28 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 fe6e25f46b55..a1047ea60ecf 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -314,19 +314,6 @@ 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) @@ -335,7 +322,7 @@ 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; @@ -358,9 +345,9 @@ 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) @@ -487,8 +474,11 @@ 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; @@ -498,10 +488,7 @@ 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); } @@ -521,13 +508,16 @@ 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; } @@ -692,7 +682,7 @@ 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; -- 2.26.2