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Mon, 07 Aug 2023 04:16:21 -0700 (PDT) From: Qi Zheng To: akpm@linux-foundation.org, david@fromorbit.com, 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, simon.horman@corigine.com, dlemoal@kernel.org Cc: 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, Qi Zheng , Muchun Song Subject: [PATCH v4 30/48] vmw_balloon: dynamically allocate the vmw-balloon shrinker Date: Mon, 7 Aug 2023 19:09:18 +0800 Message-Id: <20230807110936.21819-31-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230807110936.21819-1-zhengqi.arch@bytedance.com> References: <20230807110936.21819-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 In preparation for implementing lockless slab shrink, use new APIs to dynamically allocate the vmw-balloon shrinker, so that it can be freed asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU read-side critical section when releasing the struct vmballoon. And we can simply exit vmballoon_init() when registering the shrinker fails. So the shrinker_registered indication is redundant, just remove it. Signed-off-by: Qi Zheng Reviewed-by: Muchun Song --- drivers/misc/vmw_balloon.c | 38 ++++++++++++-------------------------- 1 file changed, 12 insertions(+), 26 deletions(-) diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c index 9ce9b9e0e9b6..ac2cdb6cdf74 100644 --- a/drivers/misc/vmw_balloon.c +++ b/drivers/misc/vmw_balloon.c @@ -380,16 +380,7 @@ struct vmballoon { /** * @shrinker: shrinker interface that is used to avoid over-inflation. */ - struct shrinker shrinker; - - /** - * @shrinker_registered: whether the shrinker was registered. - * - * The shrinker interface does not handle gracefully the removal of - * shrinker that was not registered before. This indication allows to - * simplify the unregistration process. - */ - bool shrinker_registered; + struct shrinker *shrinker; }; static struct vmballoon balloon; @@ -1568,29 +1559,27 @@ static unsigned long vmballoon_shrinker_count(struct shrinker *shrinker, static void vmballoon_unregister_shrinker(struct vmballoon *b) { - if (b->shrinker_registered) - unregister_shrinker(&b->shrinker); - b->shrinker_registered = false; + shrinker_free(b->shrinker); } static int vmballoon_register_shrinker(struct vmballoon *b) { - int r; - /* Do nothing if the shrinker is not enabled */ if (!vmwballoon_shrinker_enable) return 0; - b->shrinker.scan_objects = vmballoon_shrinker_scan; - b->shrinker.count_objects = vmballoon_shrinker_count; - b->shrinker.seeks = DEFAULT_SEEKS; + b->shrinker = shrinker_alloc(0, "vmw-balloon"); + if (!b->shrinker) + return -ENOMEM; - r = register_shrinker(&b->shrinker, "vmw-balloon"); + b->shrinker->scan_objects = vmballoon_shrinker_scan; + b->shrinker->count_objects = vmballoon_shrinker_count; + b->shrinker->seeks = DEFAULT_SEEKS; + b->shrinker->private_data = b; - if (r == 0) - b->shrinker_registered = true; + shrinker_register(b->shrinker); - return r; + return 0; } /* @@ -1883,7 +1872,7 @@ static int __init vmballoon_init(void) error = vmballoon_register_shrinker(&balloon); if (error) - goto fail; + return error; /* * Initialization of compaction must be done after the call to @@ -1905,9 +1894,6 @@ static int __init vmballoon_init(void) vmballoon_debugfs_init(&balloon); return 0; -fail: - vmballoon_unregister_shrinker(&balloon); - return error; } /*