From mboxrd@z Thu Jan 1 00:00:00 1970 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 378C2C77B60 for ; Tue, 28 Mar 2023 23:23:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229477AbjC1XXy (ORCPT ); Tue, 28 Mar 2023 19:23:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229586AbjC1XW2 (ORCPT ); Tue, 28 Mar 2023 19:22:28 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25DE63A9A for ; Tue, 28 Mar 2023 16:22:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A35AF619F9 for ; Tue, 28 Mar 2023 23:22:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01C14C433D2; Tue, 28 Mar 2023 23:22:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1680045738; bh=x1kPBkPDzXzMZL6NEgrHHPhfSZNpgHq6ecoFfH6vbj8=; h=Date:To:From:Subject:From; b=mOGFVXcuKaK0SjoBYawj4EdcI4nwou79D+rDrZAnYp3rfQsLbOuu/L/GotNpK/h3F N30x5Xu/UFtLOOYYNqFOsq81sDP3FPIbv7Q94KevSl+238fInZowUJ5PRGDLwHzQQJ rafZCsn84mrAb7m74p+xCCTsX64Q8aQ7GZvf2AsU= Date: Tue, 28 Mar 2023 16:22:17 -0700 To: mm-commits@vger.kernel.org, zhengqi.arch@bytedance.com, vbabka@suse.cz, sultan@kerneltoast.com, shy828301@gmail.com, shakeelb@google.com, roman.gushchin@linux.dev, penguin-kernel@i-love.sakura.ne.jp, paulmck@kernel.org, muchun.song@linux.dev, mhocko@kernel.org, hannes@cmpxchg.org, david@redhat.com, dave@stgolabs.net, christian.koenig@amd.com, tkhai@ya.ru, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-vmscan-add-shrinker_srcu_generation.patch removed from -mm tree Message-Id: <20230328232218.01C14C433D2@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm: vmscan: add shrinker_srcu_generation has been removed from the -mm tree. Its filename was mm-vmscan-add-shrinker_srcu_generation.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Kirill Tkhai Subject: mm: vmscan: add shrinker_srcu_generation Date: Mon, 13 Mar 2023 19:28:15 +0800 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. Link: https://lkml.kernel.org/r/20230313112819.38938-5-zhengqi.arch@bytedance.com Signed-off-by: Kirill Tkhai Signed-off-by: Qi Zheng Acked-by: Vlastimil Babka Acked-by: Roman Gushchin Cc: Christian König Cc: David Hildenbrand Cc: Davidlohr Bueso Cc: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Paul E. McKenney Cc: Shakeel Butt Cc: Sultan Alsawaf Cc: Tetsuo Handa Cc: Yang Shi Signed-off-by: Andrew Morton --- mm/vmscan.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) --- a/mm/vmscan.c~mm-vmscan-add-shrinker_srcu_generation +++ a/mm/vmscan.c @@ -204,6 +204,7 @@ static void set_task_reclaim_state(struc 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 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(g { 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(g 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 g { 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 g 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 g 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); _ Patches currently in -mm which might be from tkhai@ya.ru are