From patchwork Fri Jun 9 08:15:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qi Zheng X-Patchwork-Id: 13273406 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 4DE63C7EE2F for ; Fri, 9 Jun 2023 08:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240181AbjFIIRj (ORCPT ); Fri, 9 Jun 2023 04:17:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51710 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240172AbjFIIRh (ORCPT ); Fri, 9 Jun 2023 04:17:37 -0400 Received: from out-25.mta0.migadu.com (out-25.mta0.migadu.com [91.218.175.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 257C62D63 for ; Fri, 9 Jun 2023 01:17:03 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1686298619; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=nWHbWur0xcsiIJRNXO9BxnEFhJfaHaB29elJK86jImY=; b=hm9r9Z4VbXL0q0p45qjdxq5imQrOSAOz6SqUl1eCzpaZLRAaEqtUbZNLqwHOsLS/xhrsvk F6qAXhDOx6pg63ZiJRsecHNM4ZqohscqAvlPCfzuoV/QxWl4sCGfpNTwhJUjW8YLxQGSP6 rDKDBy+yd9VO521dSPMx3hA8aLDd61s= From: Qi Zheng To: akpm@linux-foundation.org Cc: david@fromorbit.com, tkhai@ya.ru, roman.gushchin@linux.dev, vbabka@suse.cz, muchun.song@linux.dev, yujie.liu@intel.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Qi Zheng Subject: [PATCH 0/7] revert shrinker_srcu related changes Date: Fri, 9 Jun 2023 08:15:11 +0000 Message-Id: <20230609081518.3039120-1-qi.zheng@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Qi Zheng Hi all, Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. After discussion, we will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So revert the shrinker_srcu related changes first. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ And hi Andrew, the commit c3b5cb881de6 ("mm: vmscan: move shrinker_debugfs_remove() before synchronize_srcu()") is still in the mm-unstable branch, you can drop it directly. This series is based on v6.4-rc5. Thanks, Qi Qi Zheng (7): Revert "mm: shrinkers: convert shrinker_rwsem to mutex" Revert "mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers()" Revert "mm: vmscan: hold write lock to reparent shrinker nr_deferred" Revert "mm: shrinkers: make count and scan in shrinker debugfs lockless" Revert "mm: vmscan: add shrinker_srcu_generation" Revert "mm: vmscan: make memcg slab shrink lockless" Revert "mm: vmscan: make global slab shrink lockless" drivers/md/dm-cache-metadata.c | 2 +- drivers/md/dm-thin-metadata.c | 2 +- fs/super.c | 2 +- mm/shrinker_debug.c | 39 ++++++---- mm/vmscan.c | 125 +++++++++++++++------------------ 5 files changed, 82 insertions(+), 88 deletions(-)