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[2620:137:e000::1:20]) by mx.google.com with ESMTP id k28-20020aa7999c000000b0065f91c28592si2191442pfh.10.2023.06.09.01.45.35; Fri, 09 Jun 2023 01:45:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linux.dev header.s=key1 header.b=hm9r9Z4V; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.dev Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240353AbjFIIRz (ORCPT + 99 others); Fri, 9 Jun 2023 04:17:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240179AbjFIIRh (ORCPT ); Fri, 9 Jun 2023 04:17:37 -0400 Received: from out-2.mta0.migadu.com (out-2.mta0.migadu.com [91.218.175.2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B8A12D7C 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 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768214074035270316?= X-GMAIL-MSGID: =?utf-8?q?1768214074035270316?= 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(-)