From patchwork Thu Jul 27 08:04:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qi Zheng X-Patchwork-Id: 13329725 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 B5001C001E0 for ; Thu, 27 Jul 2023 08:31:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234339AbjG0IbI (ORCPT ); Thu, 27 Jul 2023 04:31:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234908AbjG0I3L (ORCPT ); Thu, 27 Jul 2023 04:29:11 -0400 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98A60903D for ; Thu, 27 Jul 2023 01:15:29 -0700 (PDT) Received: by mail-pf1-x436.google.com with SMTP id d2e1a72fcca58-686f6231bdeso114060b3a.1 for ; Thu, 27 Jul 2023 01:15:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1690445686; x=1691050486; 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=dp1PQp+5gTkm4DG/kxrQVAZ0rB7KyI/rGW6TiEnUaUw=; b=MqP96Bm9fq0jb+xCLhNx3qXYFKB4F/mSOAZlWu4Jm1FlamJjkRz7LK2fKulsbN+LSn l0VYmbaw65P+tcDvLp0k7E9haUqgvwJAWE6OpcHuKyrg08ULwJDb+WP/772xDJT911c7 7zPxywkNsS4PFeXucHGoe87Ta2cj9HmvnL8UOM3A93e62EY5SL9atdoN3JsX9JTRnBw0 N6tNSQutP8zPFknN6y/kLRagvKGA92ju9GvGVVfPXxOrB71gJD9FTKmQ9dcanmCJl0Mj XtJnZ+1w8I86OoTRE6esFmZWRayBNnTg+LYaUjuJMZuWhMZx1Zg8pNqMQLhwRUKqGlU2 KUKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690445686; x=1691050486; 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=dp1PQp+5gTkm4DG/kxrQVAZ0rB7KyI/rGW6TiEnUaUw=; b=jRK/Yp350gad2sAWCicUs3ETnvL+RsVJxgkTh0t0nnaRH7j3ERdL+lglITULeHBVpg mqnYqGbUgeDfIgyVAXV7gmXR7a/tEAoyibik0TSFNb38eGl7n9adp693IrJ/8nq1OWAh 7D+Y+MVT1ER1G2gm9a5HCcaSYO2E9tnS/+tI9HxdF8/Axt4We6GdQr751wgI7BVP/BiE 8m89RerMh9yP5s6IPJM9ZUko6riKrtNQRJ6x/kyAdZpoqENAko1fliZYXGPIab/BSpQh Lmyew0fg9G4HDc2VtREMAdsecPo9ntHtqj+iiNArj7izO/AKI5zfc1xsjkcIuXFOjW2A FNDg== X-Gm-Message-State: ABy/qLaqXu+I25ON+W1VSjRaTrVc1LGRI5h8W+PdqmS+PWE1PUmFR4Ex o5zt1m3nNLeAiMMku2uYJWNLRA== X-Google-Smtp-Source: APBJJlEKqhcD6VVO3jjfSZcBy2+bKwiVuLncssOJVtvwGRfgIG5yeQydG6zmLtiTondHAX8WGQ4FoA== X-Received: by 2002:a05:6a20:841d:b0:133:7a67:b477 with SMTP id c29-20020a056a20841d00b001337a67b477mr6364506pzd.1.1690445686337; Thu, 27 Jul 2023 01:14:46 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.147]) by smtp.gmail.com with ESMTPSA id j8-20020aa78d08000000b006828e49c04csm885872pfe.75.2023.07.27.01.14.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Jul 2023 01:14:45 -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 , Muchun Song Subject: [PATCH v3 44/49] drm/ttm: introduce pool_shrink_rwsem Date: Thu, 27 Jul 2023 16:04:57 +0800 Message-Id: <20230727080502.77895-45-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230727080502.77895-1-zhengqi.arch@bytedance.com> References: <20230727080502.77895-1-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 c9c9618c0dce..38b4c280725c 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 c55c07c3f0cb..025c8070dd86 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -103,8 +103,6 @@ struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...); void shrinker_register(struct shrinker *shrinker); void shrinker_free(struct shrinker *shrinker); -extern void synchronize_shrinkers(void); - #ifdef CONFIG_SHRINKER_DEBUG extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...); diff --git a/mm/shrinker.c b/mm/shrinker.c index 3ab301ff122d..a27779ed3798 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -650,18 +650,3 @@ void shrinker_free(struct shrinker *shrinker) kfree(shrinker); } EXPORT_SYMBOL_GPL(shrinker_free); - -/** - * 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);