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[73.93.239.127]) by smtp.gmail.com with ESMTPSA id d4sm20610758pfo.127.2020.12.14.14.37.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Dec 2020 14:37:48 -0800 (PST) From: Yang Shi To: guro@fb.com, ktkhai@virtuozzo.com, 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: [v2 PATCH 4/9] mm: vmscan: use a new flag to indicate shrinker is registered Date: Mon, 14 Dec 2020 14:37:17 -0800 Message-Id: <20201214223722.232537-5-shy828301@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201214223722.232537-1-shy828301@gmail.com> References: <20201214223722.232537-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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. Introduce a new flag to indicate if shrinker is registered or not. Signed-off-by: Yang Shi --- 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 9b31b9c419ec..16c9d2aeeb26 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -378,6 +378,7 @@ 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); } @@ -397,13 +398,17 @@ 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