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[49.186.119.116]) by smtp.gmail.com with ESMTPSA id r5-20020a62e405000000b00666e649ca46sm10751809pfh.101.2023.07.26.00.26.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jul 2023 00:26:06 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1qOYuK-00AfFC-0I; Wed, 26 Jul 2023 17:26:04 +1000 Date: Wed, 26 Jul 2023 17:26:04 +1000 From: Dave Chinner To: Qi Zheng Cc: akpm@linux-foundation.org, tkhai@ya.ru, vbabka@suse.cz, roman.gushchin@linux.dev, djwong@kernel.org, brauner@kernel.org, paulmck@kernel.org, tytso@mit.edu, steven.price@arm.com, cel@kernel.org, senozhatsky@chromium.org, yujie.liu@intel.com, gregkh@linuxfoundation.org, muchun.song@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-erofs@lists.ozlabs.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, linux-mtd@lists.infradead.org, rcu@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-bcache@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2 03/47] mm: shrinker: add infrastructure for dynamically allocating shrinker Message-ID: References: <20230724094354.90817-1-zhengqi.arch@bytedance.com> <20230724094354.90817-4-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230724094354.90817-4-zhengqi.arch@bytedance.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: DBF36180005 X-Stat-Signature: ojm1zi6xx66osk5e6wiuktgj6bkdwes6 X-Rspam-User: X-HE-Tag: 1690356368-702411 X-HE-Meta: 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 JJ1RXOWO +10/K+tuns9ijcP0UX4ymaa3OaG84353GMnOYZiEZy/9egCZbqT0/2B5LOfkhe4nkSZ77RoWDAv3THUn2Iw+Xl43Q+guZCqrgAbckmipmNRZHrURKMmxwd6rAZ1gkO59jL4TZ36C2p2FM3UiCOxoj3oJkATfUQkMm8AmRG/rOmzZ7kuCUDbFuXVEdNgGgw5noRUBCBMb5GkopAKfusPzsOCJciEp7gdA6D/pOR2MwLhMxKprRgJgf0MhHp0avVrWNBRIrpEyGpqqHgCEwxoCca4QdXA0QIh0Y5wpewq2NYNKeR/KL8KpxO12aWqYyNysSkyEdb7Q6wu75lqOfOwYEEE6Svgt0Kl3yK6ViuVIOF980HaZ/pBWdQneeuls1frQaF6Vgi9Xoteao/7d94KsHPHBDIOiBQxVbBGEvkbn6y6v7bw095ZS5+dFAnOxt1Np9DGyz X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jul 24, 2023 at 05:43:10PM +0800, Qi Zheng wrote: > Currently, the shrinker instances can be divided into the following three > types: > > a) global shrinker instance statically defined in the kernel, such as > workingset_shadow_shrinker. > > b) global shrinker instance statically defined in the kernel modules, such > as mmu_shrinker in x86. > > c) shrinker instance embedded in other structures. > > For case a, the memory of shrinker instance is never freed. For case b, > the memory of shrinker instance will be freed after synchronize_rcu() when > the module is unloaded. For case c, the memory of shrinker instance will > be freed along with the structure it is embedded in. > > In preparation for implementing lockless slab shrink, we need to > dynamically allocate those shrinker instances in case c, then the memory > can be dynamically freed alone by calling kfree_rcu(). > > So this commit adds the following new APIs for dynamically allocating > shrinker, and add a private_data field to struct shrinker to record and > get the original embedded structure. > > 1. shrinker_alloc() > > Used to allocate shrinker instance itself and related memory, it will > return a pointer to the shrinker instance on success and NULL on failure. > > 2. shrinker_free_non_registered() > > Used to destroy the non-registered shrinker instance. This is a bit nasty > > 3. shrinker_register() > > Used to register the shrinker instance, which is same as the current > register_shrinker_prepared(). > > 4. shrinker_unregister() rename this "shrinker_free()" and key the two different freeing cases on the SHRINKER_REGISTERED bit rather than mostly duplicating the two. void shrinker_free(struct shrinker *shrinker) { struct dentry *debugfs_entry = NULL; int debugfs_id; if (!shrinker) return; down_write(&shrinker_rwsem); if (shrinker->flags & SHRINKER_REGISTERED) { list_del(&shrinker->list); debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id); } else if (IS_ENABLED(CONFIG_SHRINKER_DEBUG)) { kfree_const(shrinker->name); } if (shrinker->flags & SHRINKER_MEMCG_AWARE) unregister_memcg_shrinker(shrinker); up_write(&shrinker_rwsem); if (debugfs_entry) shrinker_debugfs_remove(debugfs_entry, debugfs_id); kfree(shrinker->nr_deferred); kfree(shrinker); } EXPORT_SYMBOL_GPL(shrinker_free); -- Dave Chinner david@fromorbit.com