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 2938FC6FD1E for ; Tue, 7 Mar 2023 22:26:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229768AbjCGW0T (ORCPT ); Tue, 7 Mar 2023 17:26:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229794AbjCGW0O (ORCPT ); Tue, 7 Mar 2023 17:26:14 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C9C687344 for ; Tue, 7 Mar 2023 14:25:31 -0800 (PST) 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 746EF6159E for ; Tue, 7 Mar 2023 22:25:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D01FAC433EF; Tue, 7 Mar 2023 22:25:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1678227926; bh=gVlcGlUXIBQPJng4XAckjDhnzoKr9KpEQx6I9GW/WcA=; h=Date:To:From:Subject:From; b=ofdU+che1YVWFdXdocQl0FA/bbtrKpS8UNFmX/Gyp0z+laTxbaiu843PAgLetNCVQ kv9xB9rEkElX4va05NzjV23BPp+z9NZc9ruc+re5fuD22qs73RLwsvd/t8gygJh9oG PHLcnMv9Oa90nvMSoaQsGiL9iBsVZp6QPoRS1psQ= Date: Tue, 07 Mar 2023 14:25:26 -0800 To: mm-commits@vger.kernel.org, zhengqi.arch@bytedance.com, sultan@kerneltoast.com, shy828301@gmail.com, shakeelb@google.com, rppt@kernel.org, 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, tkhai@ya.ru, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-vmscan-add-shrinker_srcu_generation.patch added to mm-unstable branch Message-Id: <20230307222526.D01FAC433EF@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: vmscan: add shrinker_srcu_generation has been added to the -mm mm-unstable branch. Its filename is mm-vmscan-add-shrinker_srcu_generation.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmscan-add-shrinker_srcu_generation.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Kirill Tkhai Subject: mm: vmscan: add shrinker_srcu_generation Date: Tue, 7 Mar 2023 14:56:01 +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 aviod 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/20230307065605.58209-5-zhengqi.arch@bytedance.com Signed-off-by: Kirill Tkhai Signed-off-by: Qi Zheng Cc: David Hildenbrand Cc: Davidlohr Bueso Cc: Johannes Weiner Cc: Michal Hocko Cc: Mike Rapoport Cc: Muchun Song Cc: Paul E. McKenney Cc: Roman Gushchin 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; @@ -782,6 +783,7 @@ 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); @@ -803,6 +805,7 @@ 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); @@ -912,18 +915,20 @@ 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, @@ -969,6 +974,11 @@ 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); @@ -1008,7 +1018,7 @@ 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 @@ -1022,6 +1032,7 @@ 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 = { @@ -1034,6 +1045,11 @@ 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 mm-vmscan-add-shrinker_srcu_generation.patch