From patchwork Mon Jul 24 09:43:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qi Zheng X-Patchwork-Id: 13324133 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45468C001DE for ; Mon, 24 Jul 2023 10:01:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232470AbjGXKBq (ORCPT ); Mon, 24 Jul 2023 06:01:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233013AbjGXKA6 (ORCPT ); Mon, 24 Jul 2023 06:00:58 -0400 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 116C55249 for ; Mon, 24 Jul 2023 02:54:32 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id 41be03b00d2f7-55b5a37acb6so327347a12.0 for ; Mon, 24 Jul 2023 02:54:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1690192409; x=1690797209; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=tgz3Agis5n4s/WxjwmGNRU8p70ZOSlVCE9Y6IFYv5Fc=; b=eiUPUGpded6z/EEpZ8kcBg2OU6CGo1gYbzczLwywLM+tiNX7NfxZ/UX56b+ECXWGVH v0+fBr9ZR2zpMAlXtEMsjJ0CP0T6ghJOZlIp4XvJRpj8mBoc0pWtxFqlQOAd5pU8ho3C /ZF88/qParVm3q/t2C5C9G6TKSIcK6iTaJcqE2ic3WbFUt7IFInWBxxki/5fOt9V+TbB A3A3KxQQy8HhELpvIDxSXQyR+9LFYaXi6y1sjrAoM0XnjPHdW4Yjr/fiDUUV6qlqOpNO kBdOBkmF9qj5RcGgCCau8brZhsZui1mwOYvY6Yl7YB6A8sVwNtEK8JeAfRs7jSuBenIO iXvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690192409; x=1690797209; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=tgz3Agis5n4s/WxjwmGNRU8p70ZOSlVCE9Y6IFYv5Fc=; b=YTjL0kr26wtOpLxC6oQuog5sx1oCYXhDd51+NmNA+xbb9tak636nOT++xFqFWaalAj Xc3GThlH2xd0TMc9iFL252RjhhXO58tkJk9DefKwih3tcs5PwJJMcDtvGn7bqTzLXO4k dw61to6Eq/v2W7FDpqGuOCEJzaS4uX3jMG+PBbO4wjmomJAqlYqxmXiJHfMXlHb1vVL2 PaZXN1lZUzjo5UAj7C1oGwRNt3UzKxvoZWsR35lohMiK4PZ3V+421kaCQgPlpffBcVho KoV8h0xyTbNHBESAYNrYo9sJOJZefumVDvnaWQz7DK8ovHJfMHkzVtyJK5soL1eCKoVK /bNQ== X-Gm-Message-State: ABy/qLYqrGUIrrfnAMT/hBLnfstn0saJxBgVRmfla+YZx4HxZAejs6xp Q7QB/h9Ih0IU47HiW60jq6qZOw== X-Google-Smtp-Source: APBJJlGQECD+YmQyidx3CbYp8mtos2ukz3b+adApuBRwpx+yQP4R50i+1wYRdDRgYwf/0cvAmnpMMg== X-Received: by 2002:a17:902:f681:b0:1b8:a469:53d8 with SMTP id l1-20020a170902f68100b001b8a46953d8mr12732513plg.0.1690192409468; Mon, 24 Jul 2023 02:53:29 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.147]) by smtp.gmail.com with ESMTPSA id d5-20020a170902c18500b001bb20380bf2sm8467233pld.13.2023.07.24.02.53.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 02:53:29 -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 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 Subject: [PATCH v2 42/47] drm/ttm: introduce pool_shrink_rwsem Date: Mon, 24 Jul 2023 17:43:49 +0800 Message-Id: <20230724094354.90817-43-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230724094354.90817-1-zhengqi.arch@bytedance.com> References: <20230724094354.90817-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Currently, the synchronize_shrinkers() is only used by TTM pool. It only requires that no shrinkers run in parallel. After we use RCU+refcount method to implement the lockless slab shrink, we can not use shrinker_rwsem or synchronize_rcu() to guarantee that all shrinker invocations have seen an update before freeing memory. So we introduce a new pool_shrink_rwsem to implement a private synchronize_shrinkers(), so as to achieve the same purpose. Signed-off-by: Qi Zheng Reviewed-by: Muchun Song --- drivers/gpu/drm/ttm/ttm_pool.c | 15 +++++++++++++++ include/linux/shrinker.h | 2 -- mm/shrinker.c | 15 --------------- 3 files changed, 15 insertions(+), 17 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c index e1eb73d0b72a..8a35fd48ec46 100644 --- a/drivers/gpu/drm/ttm/ttm_pool.c +++ b/drivers/gpu/drm/ttm/ttm_pool.c @@ -74,6 +74,7 @@ static struct ttm_pool_type global_dma32_uncached[MAX_ORDER + 1]; static spinlock_t shrinker_lock; static struct list_head shrinker_list; static struct shrinker *mm_shrinker; +static DECLARE_RWSEM(pool_shrink_rwsem); /* Allocate pages of size 1 << order with the given gfp_flags */ static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags, @@ -317,6 +318,7 @@ static unsigned int ttm_pool_shrink(void) unsigned int num_pages; struct page *p; + down_read(&pool_shrink_rwsem); spin_lock(&shrinker_lock); pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list); list_move_tail(&pt->shrinker_list, &shrinker_list); @@ -329,6 +331,7 @@ static unsigned int ttm_pool_shrink(void) } else { num_pages = 0; } + up_read(&pool_shrink_rwsem); return num_pages; } @@ -572,6 +575,18 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev, } EXPORT_SYMBOL(ttm_pool_init); +/** + * synchronize_shrinkers - Wait for all running shrinkers to complete. + * + * This is useful to guarantee that all shrinker invocations have seen an + * update, before freeing memory, similar to rcu. + */ +static void synchronize_shrinkers(void) +{ + down_write(&pool_shrink_rwsem); + up_write(&pool_shrink_rwsem); +} + /** * ttm_pool_fini - Cleanup a pool * diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index e464b4e9be0e..23ea9360c5d8 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -105,8 +105,6 @@ void shrinker_free_non_registered(struct shrinker *shrinker); void shrinker_register(struct shrinker *shrinker); void shrinker_unregister(struct shrinker *shrinker); -extern void synchronize_shrinkers(void); - #ifdef CONFIG_SHRINKER_DEBUG extern int shrinker_debugfs_add(struct shrinker *shrinker); extern struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker, diff --git a/mm/shrinker.c b/mm/shrinker.c index 2f3635ad1b45..3c4d3fe2fa17 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -660,18 +660,3 @@ void shrinker_unregister(struct shrinker *shrinker) kfree(shrinker); } EXPORT_SYMBOL(shrinker_unregister); - -/** - * synchronize_shrinkers - Wait for all running shrinkers to complete. - * - * This is equivalent to calling unregister_shrink() and register_shrinker(), - * but atomically and with less overhead. This is useful to guarantee that all - * shrinker invocations have seen an update, before freeing memory, similar to - * rcu. - */ -void synchronize_shrinkers(void) -{ - down_write(&shrinker_rwsem); - up_write(&shrinker_rwsem); -} -EXPORT_SYMBOL(synchronize_shrinkers);