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 8DC9EC61DA4 for ; Mon, 13 Mar 2023 11:30:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230310AbjCMLan (ORCPT ); Mon, 13 Mar 2023 07:30:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230338AbjCMLa3 (ORCPT ); Mon, 13 Mar 2023 07:30:29 -0400 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80E5D5B5D1 for ; Mon, 13 Mar 2023 04:30:03 -0700 (PDT) Received: by mail-pg1-x52b.google.com with SMTP id x37so2227816pga.1 for ; Mon, 13 Mar 2023 04:30:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1678707003; 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=joJBORpGAhUrTa0QaRmWtbHEppwsJHnBnzSS2GFBqpE=; b=gxoAK0RJLeAUG9DMQX3AJ19hEgYUC73gn5qDU+xe20VchIqQl4+4Bs8TMoR+xUoHKj ND9SsfWlrkOJpCkSW9SdC0rMfbp2pkoC+L+Zsl8WbNt1tGBTAG2LXwZTOyMQ1iLcCwQd GxK8VSLfc4QaraebduBNkUss03AkdhgD0s4yXld1S43G6GFxDxgVa30i3fDKmLe2+vsn L0khGXfZPxYQ4maITGQLyGizgnKgpvbt2obFC6FA/0459J8cOE4CnMELpfc1XfocweG3 UCt1lbaasgjVAeNzd0lchgP8FL0nLDv/KuKuOjPDpVlt6/LjMfKic6NSPuZGnknpbpu6 jdFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678707003; 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=joJBORpGAhUrTa0QaRmWtbHEppwsJHnBnzSS2GFBqpE=; b=DoSFHOjibqoqPPp/r0SL8YX+I0VcsqopQhiotEnSi9PpWyYkY52mxKdQ9aflGPH/1o OZasjuqFarBa1P4o59cIvzAxV66ldxhZy/IVjXXPcf3raf0vhHdX5DRTp3ZaUpySAqw2 bG5HZfLjBEDPfh9wS3M923NxECHxQ++c6IdgYblangee23hQAA7XnczwQL8vVRa0qJqs Fm1P7yBvvHztE06DvSn8eQWWp555qlT9Cuyos5NE2YVHboRxk0dZL0UVVr58PS9nsVkw csOIGD12MMqk6yFDSdgm9Ux+V8jcgKcoWje8qzoFvifVCW0dk+J4zhMXwu7Pus1uI+Qn lXNg== X-Gm-Message-State: AO0yUKUCUgmbsQ11bG8kWcUFojFjcpukxQgB6gFCWZ2VXJa15jZHx6/V 15yT/nv07ctoH/HCc3d3DAbnOA== X-Google-Smtp-Source: AK7set8YFjpOWP7oOMMANTE81hjqmcZGdje1Alhj8F/KolKsPGx7n3vdYEg4ks+PCVoaRcuIXePCBQ== X-Received: by 2002:a05:6a00:2148:b0:606:d3d1:4cc4 with SMTP id o8-20020a056a00214800b00606d3d14cc4mr10843183pfk.3.1678707003039; Mon, 13 Mar 2023 04:30:03 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.229]) by smtp.gmail.com with ESMTPSA id n2-20020a654882000000b0050300a7c8c2sm4390827pgs.89.2023.03.13.04.29.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Mar 2023 04:30:02 -0700 (PDT) From: Qi Zheng To: akpm@linux-foundation.org, tkhai@ya.ru, vbabka@suse.cz, christian.koenig@amd.com, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com Cc: sultan@kerneltoast.com, dave@stgolabs.net, penguin-kernel@I-love.SAKURA.ne.jp, paulmck@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng Subject: [PATCH v5 4/8] mm: vmscan: add shrinker_srcu_generation Date: Mon, 13 Mar 2023 19:28:15 +0800 Message-Id: <20230313112819.38938-5-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230313112819.38938-1-zhengqi.arch@bytedance.com> References: <20230313112819.38938-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kirill Tkhai After we make slab shrink lockless with SRCU, the longest sleep unregister_shrinker() will be a sleep waiting for all do_shrink_slab() calls. To avoid long unbreakable action in the unregister_shrinker(), add shrinker_srcu_generation to restore a check similar to the rwsem_is_contendent() check that we had before. And for memcg slab shrink, we unlock SRCU and continue iterations from the next shrinker id. Signed-off-by: Kirill Tkhai Signed-off-by: Qi Zheng Acked-by: Vlastimil Babka --- mm/vmscan.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index ce7834030f75..5c2a22454320 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -204,6 +204,7 @@ static void set_task_reclaim_state(struct task_struct *task, LIST_HEAD(shrinker_list); DECLARE_RWSEM(shrinker_rwsem); DEFINE_SRCU(shrinker_srcu); +static atomic_t shrinker_srcu_generation = ATOMIC_INIT(0); #ifdef CONFIG_MEMCG static int shrinker_nr_max; @@ -776,6 +777,7 @@ void unregister_shrinker(struct shrinker *shrinker) debugfs_entry = shrinker_debugfs_remove(shrinker); up_write(&shrinker_rwsem); + atomic_inc(&shrinker_srcu_generation); synchronize_srcu(&shrinker_srcu); debugfs_remove_recursive(debugfs_entry); @@ -797,6 +799,7 @@ void synchronize_shrinkers(void) { down_write(&shrinker_rwsem); up_write(&shrinker_rwsem); + atomic_inc(&shrinker_srcu_generation); synchronize_srcu(&shrinker_srcu); } EXPORT_SYMBOL(synchronize_shrinkers); @@ -906,18 +909,20 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, { struct shrinker_info *info; unsigned long ret, freed = 0; - int srcu_idx; - int i; + int srcu_idx, generation; + int i = 0; if (!mem_cgroup_online(memcg)) return 0; +again: srcu_idx = srcu_read_lock(&shrinker_srcu); info = shrinker_info_srcu(memcg, nid); if (unlikely(!info)) goto unlock; - for_each_set_bit(i, info->map, info->map_nr_max) { + generation = atomic_read(&shrinker_srcu_generation); + for_each_set_bit_from(i, info->map, info->map_nr_max) { struct shrink_control sc = { .gfp_mask = gfp_mask, .nid = nid, @@ -963,6 +968,11 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, set_shrinker_bit(memcg, nid, i); } freed += ret; + if (atomic_read(&shrinker_srcu_generation) != generation) { + srcu_read_unlock(&shrinker_srcu, srcu_idx); + i++; + goto again; + } } unlock: srcu_read_unlock(&shrinker_srcu, srcu_idx); @@ -1002,7 +1012,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, { unsigned long ret, freed = 0; struct shrinker *shrinker; - int srcu_idx; + int srcu_idx, generation; /* * The root memcg might be allocated even though memcg is disabled @@ -1016,6 +1026,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, srcu_idx = srcu_read_lock(&shrinker_srcu); + generation = atomic_read(&shrinker_srcu_generation); list_for_each_entry_srcu(shrinker, &shrinker_list, list, srcu_read_lock_held(&shrinker_srcu)) { struct shrink_control sc = { @@ -1028,6 +1039,11 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, if (ret == SHRINK_EMPTY) ret = 0; freed += ret; + + if (atomic_read(&shrinker_srcu_generation) != generation) { + freed = freed ? : 1; + break; + } } srcu_read_unlock(&shrinker_srcu, srcu_idx); -- 2.20.1