From nobody Thu Sep 11 10:24:24 2025 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 01872C05027 for ; Mon, 20 Feb 2023 09:17:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231510AbjBTJRe (ORCPT ); Mon, 20 Feb 2023 04:17:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231495AbjBTJRa (ORCPT ); Mon, 20 Feb 2023 04:17:30 -0500 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6659E1040A for ; Mon, 20 Feb 2023 01:17:04 -0800 (PST) Received: by mail-pl1-x631.google.com with SMTP id u17so678257plh.6 for ; Mon, 20 Feb 2023 01:17:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; t=1676884624; 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=OSu6LoDi3bt+On14RPrDb/428OOXZNPo77LIFm1Bi28=; b=neiTcExIi57fl2R7QOvc3r3ELyzAtnMxW9GBNNCltkuMHmkXl5ZK+7Q0xCR6QpS+bt hP0XX6ZlR6iZxJOKblWlpeGKlK0XFXTJ6YTh8xf01BgvCpVSzBAdsU1eNWAu/zmWpkI3 9p1TCdObRxhi5YMuGSLQ1T3HSRXNro+TSsI76hsUHs5DW20YstK9espDPHnwdEXtao3l lajZuuPnoZK/Rm/vt/YViwwLTzZW/RtdXkdVPp+DvpozOWqhFL7zaeOqjL7CkS5IB/Uq XEBgboArtxfsBttqiHviM+ZB06ohsgBSRsBrlb3EsBlg+YZoeTyyZ3T9K3z2UfsI7PLd kbmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1676884624; 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=OSu6LoDi3bt+On14RPrDb/428OOXZNPo77LIFm1Bi28=; b=lWlbCcn+OqhK8MU6bYfP91TQ0BYoHIiFYrS/F6e/PCrJli3JxO2GgbIrXR/umFGk/r Xpkfe1wqAVzpV0lYI9W2+FCf7YskgR+1GttngZ2OnePEdtTHBXdNvUHwxcM1AVTRUibA zE+h6H40wdYrnsHtwG9B2Exh+sTzXs+T3Wp9StrajjQqk5VBGbeSrtkUOwLprX7gk8xJ dJphTIr5TypqLhCXjY/btJPxhrP1MTBxIRZ7n/TFO0FyckUlIkWOvFk9bur22t9Ro62z jCJsp3q/8rUrRLG1EPxrq8tOIDuAyn1SMi4eEOQJn7jFaj7sQ6PjOzrzWtmrx+UAI+Bo Pxag== X-Gm-Message-State: AO0yUKWOsgSfhDsIMVxSU9rCrCx2nJEE0it8KaR+kPLaIGQwXCe0xH9U LZyHBTC0Vk60rFVKIOFaiVTQlw== X-Google-Smtp-Source: AK7set/Qfx+rPSFCLub0/LUO6j0gUaT7gq5PlaRfKArK9fwOowwRmHnhYd2zrA9jqT1wfk9fQyhMBA== X-Received: by 2002:a17:90a:bf0d:b0:233:a836:15f4 with SMTP id c13-20020a17090abf0d00b00233a83615f4mr528696pjs.1.1676884623852; Mon, 20 Feb 2023 01:17:03 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.229]) by smtp.gmail.com with ESMTPSA id fs13-20020a17090af28d00b002339195a47bsm432382pjb.53.2023.02.20.01.16.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Feb 2023 01:17:03 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com Cc: tkhai@ya.ru, 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 1/5] mm: vmscan: make global slab shrink lockless Date: Mon, 20 Feb 2023 17:16:33 +0800 Message-Id: <20230220091637.64865-2-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230220091637.64865-1-zhengqi.arch@bytedance.com> References: <20230220091637.64865-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The shrinker_rwsem is a global lock in shrinkers subsystem, it is easy to cause blocking in the following cases: a. the write lock of shrinker_rwsem was held for too long. For example, there are many memcgs in the system, which causes some paths to hold locks and traverse it for too long. (e.g. expand_shrinker_info()) b. the read lock of shrinker_rwsem was held for too long, and a writer came at this time. Then this writer will be forced to wait and block all subsequent readers. For example: - be scheduled when the read lock of shrinker_rwsem is held in do_shrink_slab() - some shrinker are blocked for too long. Like the case mentioned in the patchset[1]. Therefore, many times in history ([2],[3],[4],[5]), some people wanted to replace shrinker_rwsem reader with SRCU, but they all gave up because SRCU was not unconditionally enabled. But now, since commit 1cd0bd06093c ("rcu: Remove CONFIG_SRCU"), the SRCU is unconditionally enabled. So it's time to use SRCU to protect readers who previously held shrinker_rwsem. [1]. https://lore.kernel.org/lkml/20191129214541.3110-1-ptikhomirov@virtuoz= zo.com/ [2]. https://lore.kernel.org/all/1437080113.3596.2.camel@stgolabs.net/ [3]. https://lore.kernel.org/lkml/1510609063-3327-1-git-send-email-penguin-= kernel@I-love.SAKURA.ne.jp/ [4]. https://lore.kernel.org/lkml/153365347929.19074.12509495712735843805.s= tgit@localhost.localdomain/ [5]. https://lore.kernel.org/lkml/20210927074823.5825-1-sultan@kerneltoast.= com/ Signed-off-by: Qi Zheng --- mm/vmscan.c | 27 +++++++++++---------------- 1 file changed, 11 insertions(+), 16 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9c1c5e8b24b8..95a3d6ddc6c1 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -202,6 +202,7 @@ static void set_task_reclaim_state(struct task_struct *= task, =20 LIST_HEAD(shrinker_list); DECLARE_RWSEM(shrinker_rwsem); +DEFINE_SRCU(shrinker_srcu); =20 #ifdef CONFIG_MEMCG static int shrinker_nr_max; @@ -699,7 +700,7 @@ void free_prealloced_shrinker(struct shrinker *shrinker) void register_shrinker_prepared(struct shrinker *shrinker) { down_write(&shrinker_rwsem); - list_add_tail(&shrinker->list, &shrinker_list); + list_add_tail_rcu(&shrinker->list, &shrinker_list); shrinker->flags |=3D SHRINKER_REGISTERED; shrinker_debugfs_add(shrinker); up_write(&shrinker_rwsem); @@ -753,13 +754,15 @@ void unregister_shrinker(struct shrinker *shrinker) return; =20 down_write(&shrinker_rwsem); - list_del(&shrinker->list); + list_del_rcu(&shrinker->list); shrinker->flags &=3D ~SHRINKER_REGISTERED; if (shrinker->flags & SHRINKER_MEMCG_AWARE) unregister_memcg_shrinker(shrinker); debugfs_entry =3D shrinker_debugfs_remove(shrinker); up_write(&shrinker_rwsem); =20 + synchronize_srcu(&shrinker_srcu); + debugfs_remove_recursive(debugfs_entry); =20 kfree(shrinker->nr_deferred); @@ -779,6 +782,7 @@ void synchronize_shrinkers(void) { down_write(&shrinker_rwsem); up_write(&shrinker_rwsem); + synchronize_srcu(&shrinker_srcu); } EXPORT_SYMBOL(synchronize_shrinkers); =20 @@ -989,6 +993,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int ni= d, { unsigned long ret, freed =3D 0; struct shrinker *shrinker; + int srcu_idx; =20 /* * The root memcg might be allocated even though memcg is disabled @@ -1000,10 +1005,10 @@ static unsigned long shrink_slab(gfp_t gfp_mask, in= t nid, if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority); =20 - if (!down_read_trylock(&shrinker_rwsem)) - goto out; + srcu_idx =3D srcu_read_lock(&shrinker_srcu); =20 - list_for_each_entry(shrinker, &shrinker_list, list) { + list_for_each_entry_srcu(shrinker, &shrinker_list, list, + srcu_read_lock_held(&shrinker_srcu)) { struct shrink_control sc =3D { .gfp_mask =3D gfp_mask, .nid =3D nid, @@ -1014,19 +1019,9 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int= nid, if (ret =3D=3D SHRINK_EMPTY) ret =3D 0; freed +=3D ret; - /* - * Bail out if someone want to register a new shrinker to - * prevent the registration from being stalled for long periods - * by parallel ongoing shrinking. - */ - if (rwsem_is_contended(&shrinker_rwsem)) { - freed =3D freed ? : 1; - break; - } } =20 - up_read(&shrinker_rwsem); -out: + srcu_read_unlock(&shrinker_srcu, srcu_idx); cond_resched(); return freed; } --=20 2.20.1 From nobody Thu Sep 11 10:24:24 2025 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 E10C1C6379F for ; Mon, 20 Feb 2023 09:17:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231458AbjBTJRQ (ORCPT ); Mon, 20 Feb 2023 04:17:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230459AbjBTJRM (ORCPT ); Mon, 20 Feb 2023 04:17:12 -0500 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49BB9FF0C for ; Mon, 20 Feb 2023 01:17:11 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id e5so1658125plg.8 for ; Mon, 20 Feb 2023 01:17:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; t=1676884631; 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=Hay0adYlVwY1IjdRfk5CKFeKCnG2WTWsVt3L/E4Vszc=; b=dzq60rThnG1eHPZmbaqIAdKnvx11jcx+9c7+Xz+Fvb8jzUNuPvxrvvoH9rxiY7bseY MwBIqKmGnnRLy9oD7KNU0IP05L8avR9WGkGCuO0KBPHzABJt+tBiqxGIQYJRYUEQ7wdc +CCtYi1ncziYhQ42cmwAoqIuU1fou5tShKZ0YV8xXDToTIOwyrRgdIk32smyOhodVlyW 8GS5Jc0N9MoRt/38dCyYzVz+zoLJ6UwCIwnPMbV9kDCk/1kPdWTnY7K7PljNojAlUkBH R//DTbH1un7fzgI87WSVUXn8bEViUtn4XHEVe68NYl5dLaXaPf0wAFPKmBBOQiZAvtXk j0mw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1676884631; 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=Hay0adYlVwY1IjdRfk5CKFeKCnG2WTWsVt3L/E4Vszc=; b=etWvqHmjeT2bd6P/vEh+qK/e1MzUclxmMW/LTH84pnOFoupjV8YofWd9TvvZkwZn/E VF0GHAWtYJ34Je+MwE2nY8ucZLb5GkdVIBCD5ngIMu5QRGy3AOoxq9UXiCFVqxPNIKyl tungdXBGWrIrodbV+AQz76MM67Y3sOcuSErnb20b+5qD7N/FhI5DpQjA0vSayza5rqJU Z3ib0eNeb/9Q3xcJvfaPyUWQd0qWCGQ2W7ApmjuAebddzkXfL2aRr/zrfyB2nLbdkPEK UjuLUQi1Ta0wQ47fBbl92dlWIxHiIiNcbne9eKxvhoUCZB6uxJi8tVRnLxPeo0W98tMR REsQ== X-Gm-Message-State: AO0yUKWLmsDtCitDsBaX5m6qGVXbj4zY6v25dKbnlJccdj0ys3FL1Ozc 0PIKxkzvDoCR9SBoPU45abQ1RQ== X-Google-Smtp-Source: AK7set+RFNh5qhT4uR8QO+C6MsDJpFzqsI6Ran0kA2qMXuWKiMKjLinzDtbzLeMxRFj33Xvv1RqpTg== X-Received: by 2002:a17:90a:ac0a:b0:230:9ae4:b5e2 with SMTP id o10-20020a17090aac0a00b002309ae4b5e2mr566508pjq.0.1676884630706; Mon, 20 Feb 2023 01:17:10 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.229]) by smtp.gmail.com with ESMTPSA id fs13-20020a17090af28d00b002339195a47bsm432382pjb.53.2023.02.20.01.17.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Feb 2023 01:17:10 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com Cc: tkhai@ya.ru, 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 2/5] mm: vmscan: make memcg slab shrink lockless Date: Mon, 20 Feb 2023 17:16:34 +0800 Message-Id: <20230220091637.64865-3-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230220091637.64865-1-zhengqi.arch@bytedance.com> References: <20230220091637.64865-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Like global slab shrink, since commit 1cd0bd06093c ("rcu: Remove CONFIG_SRCU"), it's time to use SRCU to protect readers who previously held shrinker_rwsem. We can test with the following script: ``` DIR=3D"/root/shrinker/memcg/mnt" do_create() { mkdir /sys/fs/cgroup/memory/test echo 200M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes for i in `seq 0 $1`; do mkdir /sys/fs/cgroup/memory/test/$i; echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs; mkdir -p $DIR/$i; done } do_mount() { for i in `seq $1 $2`; do mount -t tmpfs $i $DIR/$i; done } do_touch() { for i in `seq $1 $2`; do echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs; dd if=3D/dev/zero of=3D$DIR/$i/file$i bs=3D1M count=3D1 & done } do_create 2000 do_mount 0 2000 do_touch 0 1000 ``` Before applying: 46.60% [kernel] [k] down_read_trylock 18.70% [kernel] [k] up_read 15.44% [kernel] [k] shrink_slab 4.37% [kernel] [k] _find_next_bit 2.75% [kernel] [k] xa_load 2.07% [kernel] [k] idr_find 1.73% [kernel] [k] do_shrink_slab 1.42% [kernel] [k] shrink_lruvec 0.74% [kernel] [k] shrink_node 0.60% [kernel] [k] list_lru_count_one After applying: 19.53% [kernel] [k] _find_next_bit 14.63% [kernel] [k] do_shrink_slab 14.58% [kernel] [k] shrink_slab 11.83% [kernel] [k] shrink_lruvec 9.33% [kernel] [k] __blk_flush_plug 6.67% [kernel] [k] mem_cgroup_iter 3.73% [kernel] [k] list_lru_count_one 2.43% [kernel] [k] shrink_node 1.96% [kernel] [k] super_cache_count 1.78% [kernel] [k] __rcu_read_unlock 1.38% [kernel] [k] __srcu_read_lock 1.30% [kernel] [k] xas_descend We can see that the readers is no longer blocked. Signed-off-by: Qi Zheng --- mm/vmscan.c | 56 ++++++++++++++++++++++++++++++----------------------- 1 file changed, 32 insertions(+), 24 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 95a3d6ddc6c1..dc47396ecd0e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -57,6 +57,7 @@ #include #include #include +#include =20 #include #include @@ -221,8 +222,21 @@ static inline int shrinker_defer_size(int nr_items) static struct shrinker_info *shrinker_info_protected(struct mem_cgroup *me= mcg, int nid) { - return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, - lockdep_is_held(&shrinker_rwsem)); + return srcu_dereference_check(memcg->nodeinfo[nid]->shrinker_info, + &shrinker_srcu, + lockdep_is_held(&shrinker_rwsem)); +} + +static struct shrinker_info *shrinker_info_srcu(struct mem_cgroup *memcg, + int nid) +{ + return srcu_dereference(memcg->nodeinfo[nid]->shrinker_info, + &shrinker_srcu); +} + +static void free_shrinker_info_rcu(struct rcu_head *head) +{ + kvfree(container_of(head, struct shrinker_info, rcu)); } =20 static int expand_one_shrinker_info(struct mem_cgroup *memcg, @@ -257,7 +271,7 @@ static int expand_one_shrinker_info(struct mem_cgroup *= memcg, defer_size - old_defer_size); =20 rcu_assign_pointer(pn->shrinker_info, new); - kvfree_rcu(old, rcu); + call_srcu(&shrinker_srcu, &old->rcu, free_shrinker_info_rcu); } =20 return 0; @@ -350,13 +364,14 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int n= id, int shrinker_id) { if (shrinker_id >=3D 0 && memcg && !mem_cgroup_is_root(memcg)) { struct shrinker_info *info; + int srcu_idx; =20 - rcu_read_lock(); - info =3D rcu_dereference(memcg->nodeinfo[nid]->shrinker_info); + srcu_idx =3D srcu_read_lock(&shrinker_srcu); + info =3D shrinker_info_srcu(memcg, nid); /* Pairs with smp mb in shrink_slab() */ smp_mb__before_atomic(); set_bit(shrinker_id, info->map); - rcu_read_unlock(); + srcu_read_unlock(&shrinker_srcu, srcu_idx); } } =20 @@ -370,7 +385,6 @@ static int prealloc_memcg_shrinker(struct shrinker *shr= inker) return -ENOSYS; =20 down_write(&shrinker_rwsem); - /* This may call shrinker, so it must use down_read_trylock() */ id =3D idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL); if (id < 0) goto unlock; @@ -404,7 +418,7 @@ static long xchg_nr_deferred_memcg(int nid, struct shri= nker *shrinker, { struct shrinker_info *info; =20 - info =3D shrinker_info_protected(memcg, nid); + info =3D shrinker_info_srcu(memcg, nid); return atomic_long_xchg(&info->nr_deferred[shrinker->id], 0); } =20 @@ -413,13 +427,13 @@ static long add_nr_deferred_memcg(long nr, int nid, s= truct shrinker *shrinker, { struct shrinker_info *info; =20 - info =3D shrinker_info_protected(memcg, nid); + info =3D shrinker_info_srcu(memcg, nid); return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); } =20 void reparent_shrinker_deferred(struct mem_cgroup *memcg) { - int i, nid; + int i, nid, srcu_idx; long nr; struct mem_cgroup *parent; struct shrinker_info *child_info, *parent_info; @@ -429,16 +443,16 @@ void reparent_shrinker_deferred(struct mem_cgroup *me= mcg) parent =3D root_mem_cgroup; =20 /* Prevent from concurrent shrinker_info expand */ - down_read(&shrinker_rwsem); + srcu_idx =3D srcu_read_lock(&shrinker_srcu); for_each_node(nid) { - child_info =3D shrinker_info_protected(memcg, nid); - parent_info =3D shrinker_info_protected(parent, nid); + child_info =3D shrinker_info_srcu(memcg, nid); + parent_info =3D shrinker_info_srcu(parent, nid); for (i =3D 0; i < shrinker_nr_max; i++) { nr =3D atomic_long_read(&child_info->nr_deferred[i]); atomic_long_add(nr, &parent_info->nr_deferred[i]); } } - up_read(&shrinker_rwsem); + srcu_read_unlock(&shrinker_srcu, srcu_idx); } =20 static bool cgroup_reclaim(struct scan_control *sc) @@ -891,15 +905,14 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask= , int nid, { struct shrinker_info *info; unsigned long ret, freed =3D 0; + int srcu_idx; int i; =20 if (!mem_cgroup_online(memcg)) return 0; =20 - if (!down_read_trylock(&shrinker_rwsem)) - return 0; - - info =3D shrinker_info_protected(memcg, nid); + srcu_idx =3D srcu_read_lock(&shrinker_srcu); + info =3D shrinker_info_srcu(memcg, nid); if (unlikely(!info)) goto unlock; =20 @@ -949,14 +962,9 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask,= int nid, set_shrinker_bit(memcg, nid, i); } freed +=3D ret; - - if (rwsem_is_contended(&shrinker_rwsem)) { - freed =3D freed ? : 1; - break; - } } unlock: - up_read(&shrinker_rwsem); + srcu_read_unlock(&shrinker_srcu, srcu_idx); return freed; } #else /* CONFIG_MEMCG */ --=20 2.20.1 From nobody Thu Sep 11 10:24:24 2025 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 17F81C636CC for ; Mon, 20 Feb 2023 09:17:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231220AbjBTJRs (ORCPT ); Mon, 20 Feb 2023 04:17:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231495AbjBTJRn (ORCPT ); Mon, 20 Feb 2023 04:17:43 -0500 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8184914981 for ; Mon, 20 Feb 2023 01:17:17 -0800 (PST) Received: by mail-pj1-x1036.google.com with SMTP id g14so645848pjb.2 for ; Mon, 20 Feb 2023 01:17:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; t=1676884637; 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=3zoWZenRiYoNEE8cLwabKUnZ2EMcSBm37bQ/nay5M2Q=; b=pwzSI/vf4Vj+GnZxNmyMXkgptBLDA76ZJ1o4OmWFlr6dQarsPx2C++HYAz6Dpn2Aht AJqCW7TXaRjGCwXrIkRHBWZUa/9Uq4ShcEkudpvCqCUfsPPUCgYIFXYWtN9++5OxpAqO gLMuad7DyF/pXHMjpwmBdYV9XSfe7U12nWp4ShfpW3jKBm3KNO+XTZT5cAaCcrQzzIV1 oqisd022sPfT5wczUD241WMl4IN/0R3a2LXx3Bxnlvt0dMus9chI20ZmPMJtAtZCf//h 6YyC4HjkwgSHI06kMieLeE16TKJuxDd6RvwRYYtadIFV1TOrOtPRFHlt9t2tMxB1hTiB KYrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1676884637; 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=3zoWZenRiYoNEE8cLwabKUnZ2EMcSBm37bQ/nay5M2Q=; b=SOqQQPWO1hlJxwFaWFEJzS4vyQ8fdb3VXNPaWjXFyW/EEauLiPKAAB2jY08jz+gXFD 6wzO/+z2PWA28aFLyB7O+TlPi+Y6Sn0QaLtLYhBkw5wmTauKOArWtcwCjDyiDHs4DXWw F6zs43lo39VLsW5g13BQqmTjpdopmv3VasXAFOfwmfl1kMu/6mesjiM69DNFl23riVZh 1Jj8W8IWiwOrs1SFHleIfVCf89QNlrW0jfCLVPnCa4hPKvnBS2g9OsIxHuaForz5CYGE wLFhNNCvicDs69h1JTEJHcGBeh/fhCPwk9G6UBLNBXE9BqyrK/CVdB8tb3tb+JyJgmer 2dAA== X-Gm-Message-State: AO0yUKWks6xla4hBOmy6BAu8ZQN+N9gTofVHGTOCfW7Jvocb11gdrh9t tO7csMOZM1nxv/ZGVd+xJDUJww== X-Google-Smtp-Source: AK7set/u/nMGrcmsUwC5AW5uACSHbng2msaMYYygQeSDbSQ22MPUA9tjyQkhFmQoA6dgXKjSY0gUIw== X-Received: by 2002:a17:90a:c915:b0:234:175:839a with SMTP id v21-20020a17090ac91500b002340175839amr660167pjt.4.1676884637069; Mon, 20 Feb 2023 01:17:17 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.229]) by smtp.gmail.com with ESMTPSA id fs13-20020a17090af28d00b002339195a47bsm432382pjb.53.2023.02.20.01.17.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Feb 2023 01:17:16 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com Cc: tkhai@ya.ru, 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 3/5] mm: shrinkers: make count and scan in shrinker debugfs lockless Date: Mon, 20 Feb 2023 17:16:35 +0800 Message-Id: <20230220091637.64865-4-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230220091637.64865-1-zhengqi.arch@bytedance.com> References: <20230220091637.64865-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Like global and memcg slab shrink, also use SRCU to make count and scan operations in memory shrinker debugfs lockless. Signed-off-by: Qi Zheng --- mm/shrinker_debug.c | 24 +++++++----------------- 1 file changed, 7 insertions(+), 17 deletions(-) diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index 39c3491e28a3..6a26e8ac40aa 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -9,6 +9,7 @@ /* defined in vmscan.c */ extern struct rw_semaphore shrinker_rwsem; extern struct list_head shrinker_list; +extern struct srcu_struct shrinker_srcu; =20 static DEFINE_IDA(shrinker_debugfs_ida); static struct dentry *shrinker_debugfs_root; @@ -49,18 +50,13 @@ static int shrinker_debugfs_count_show(struct seq_file = *m, void *v) struct mem_cgroup *memcg; unsigned long total; bool memcg_aware; - int ret, nid; + int ret, nid, srcu_idx; =20 count_per_node =3D kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL= ); if (!count_per_node) return -ENOMEM; =20 - ret =3D down_read_killable(&shrinker_rwsem); - if (ret) { - kfree(count_per_node); - return ret; - } - rcu_read_lock(); + srcu_idx =3D srcu_read_lock(&shrinker_srcu); =20 memcg_aware =3D shrinker->flags & SHRINKER_MEMCG_AWARE; =20 @@ -91,8 +87,7 @@ static int shrinker_debugfs_count_show(struct seq_file *m= , void *v) } } while ((memcg =3D mem_cgroup_iter(NULL, memcg, NULL)) !=3D NULL); =20 - rcu_read_unlock(); - up_read(&shrinker_rwsem); + srcu_read_unlock(&shrinker_srcu, srcu_idx); =20 kfree(count_per_node); return ret; @@ -115,9 +110,8 @@ static ssize_t shrinker_debugfs_scan_write(struct file = *file, .gfp_mask =3D GFP_KERNEL, }; struct mem_cgroup *memcg =3D NULL; - int nid; + int nid, srcu_idx; char kbuf[72]; - ssize_t ret; =20 read_len =3D size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1); if (copy_from_user(kbuf, buf, read_len)) @@ -146,11 +140,7 @@ static ssize_t shrinker_debugfs_scan_write(struct file= *file, return -EINVAL; } =20 - ret =3D down_read_killable(&shrinker_rwsem); - if (ret) { - mem_cgroup_put(memcg); - return ret; - } + srcu_idx =3D srcu_read_lock(&shrinker_srcu); =20 sc.nid =3D nid; sc.memcg =3D memcg; @@ -159,7 +149,7 @@ static ssize_t shrinker_debugfs_scan_write(struct file = *file, =20 shrinker->scan_objects(shrinker, &sc); =20 - up_read(&shrinker_rwsem); + srcu_read_unlock(&shrinker_srcu, srcu_idx); mem_cgroup_put(memcg); =20 return size; --=20 2.20.1 From nobody Thu Sep 11 10:24:24 2025 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 969AAC05027 for ; Mon, 20 Feb 2023 09:17:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231518AbjBTJRx (ORCPT ); Mon, 20 Feb 2023 04:17:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231486AbjBTJRt (ORCPT ); Mon, 20 Feb 2023 04:17:49 -0500 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62FFF144AE for ; Mon, 20 Feb 2023 01:17:24 -0800 (PST) Received: by mail-pj1-x1035.google.com with SMTP id qi12-20020a17090b274c00b002341621377cso430187pjb.2 for ; Mon, 20 Feb 2023 01:17:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; t=1676884644; 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=+SuOsoPKf5aCTrdN4oo5ZtKUiUHbFHnkKOWfb3ggCgM=; b=JxT0r83NllZWDrv7JUbi57ga92yM+aV9REzj4acVWyDEC0qP6CkyEbEtUoBJBuS9q0 EmuU2mv0gSa+rVWs9ezOVY7JDMeIZ43k4AXpUSAQB6AdIxCSGzjOaPZ6AwD8FZdu+xj8 KqBK8u5KJuURh/jBiBPwgQcLVYo8QdvgjooE8iFX5K/C+5c1neFrb20RGiwO7pLYhkpx Pm7zBDLdADM1l0+KQy41Ws2iuIjA3OuXyqw27+xYBk0HctZU8tWkikX0xOU4A6qvcPuI IeHxUsqC/EryGaQnmdCJLqENq3+l53MZEuHQ8WxAIARks9MMf6XnteE6OVTM6echH0ty jkKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1676884644; 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=+SuOsoPKf5aCTrdN4oo5ZtKUiUHbFHnkKOWfb3ggCgM=; b=xAt1Alxft8oxvSfZXpSvUZcyKgXyXhqDZPusn6MOB9aRmpWzyqBXZpQQ5cuxRupouC eFzrr6EsqdASf6kXPkX0eEzD4jKKirJuM1KuQk0nBulQMyXUD8zmXftN+lW2JyvJIf6F pbbCmglby/tpjz0wtG596AT/g+odG1411y8rXrDqZA8mD4F4zZxO09/HbBAQaL0pquz8 cSJe+APghEoiW2bWLjmElVmEJzlyS18OZiEHvu7R433uvva91JpY4acS1w/3WqIx0eHh 0dqMVCGHFdqOYkoSzLhLvFt+jJSqAwDuknWsNNvTe8A1TuoVD6a+BsJ6Prfl7NHvqloS 7lJg== X-Gm-Message-State: AO0yUKVvn0Bt7pEs2rTHc1K3qzufEqfJAkN5SjqUFlYojGyjvMv1ITy+ AhLyVVBD3v8yCreJaY1hD9eisg== X-Google-Smtp-Source: AK7set9Jss6nYpleTWMKLk37JYg5U2t/GE2b3ogkN+P0mI3dj50eWKwdpAoiMz4LEqWxjmoXlXyuDQ== X-Received: by 2002:a17:90a:a516:b0:234:9d30:84ff with SMTP id a22-20020a17090aa51600b002349d3084ffmr950101pjq.3.1676884643904; Mon, 20 Feb 2023 01:17:23 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.229]) by smtp.gmail.com with ESMTPSA id fs13-20020a17090af28d00b002339195a47bsm432382pjb.53.2023.02.20.01.17.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Feb 2023 01:17:23 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com Cc: tkhai@ya.ru, 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 4/5] mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers() Date: Mon, 20 Feb 2023 17:16:36 +0800 Message-Id: <20230220091637.64865-5-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230220091637.64865-1-zhengqi.arch@bytedance.com> References: <20230220091637.64865-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Now there are no readers of shrinker_rwsem, so synchronize_shrinkers() does not need to hold the writer of shrinker_rwsem to wait for all running shinkers to complete, synchronize_srcu() is enough. Signed-off-by: Qi Zheng --- mm/vmscan.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index dc47396ecd0e..b8da56beba96 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -787,15 +787,11 @@ EXPORT_SYMBOL(unregister_shrinker); /** * synchronize_shrinkers - Wait for all running shrinkers to complete. * - * This is equivalent to calling unregister_shrink() and register_shrinker= (), - * but atomically and with less overhead. This is useful to guarantee that= all - * shrinker invocations have seen an update, before freeing memory, simila= r to - * rcu. + * This is useful to guarantee that all shrinker invocations have seen an + * update, before freeing memory. */ void synchronize_shrinkers(void) { - down_write(&shrinker_rwsem); - up_write(&shrinker_rwsem); synchronize_srcu(&shrinker_srcu); } EXPORT_SYMBOL(synchronize_shrinkers); --=20 2.20.1 From nobody Thu Sep 11 10:24:24 2025 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 4ADD5C05027 for ; Mon, 20 Feb 2023 09:17:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231519AbjBTJRi (ORCPT ); Mon, 20 Feb 2023 04:17:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58028 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231500AbjBTJRd (ORCPT ); Mon, 20 Feb 2023 04:17:33 -0500 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B78A915543 for ; Mon, 20 Feb 2023 01:17:30 -0800 (PST) Received: by mail-pj1-x1036.google.com with SMTP id co23-20020a17090afe9700b002341fadc370so539917pjb.1 for ; Mon, 20 Feb 2023 01:17:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; 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=3B7sNafZtBlgHmh5fpLAa14mnyUBnuiEHhgxOSu4EUY=; b=4puz4Jgz93txeceBh3fQ+lEdkKu9A4lOtC1kYgX78UKROjsP3O5+Y11jVMsovlB8oU sXuaRzKA6g9H9MXb3TdaF5sp9f/QMmV6iVKEx444zjffMm5LRNXcvYaal2t+iybJaLjY dOAt6AzfkgtaTHsJmUt79SpRjjglW8OOcC+KtEe+U5VqwR2qSZOga5VUjMCAWJRD00IM JG/qWE7eie2G7sZ4cJOwULL9sO4k8JkKSdEghpO73ZZLKfjRUL1R74gz0k7djhVwirUQ TM5T4chfi9rC4wta62Q+8DdRwAl1M2SQDAocd2oBCkh1qD+vWeFfRIBKkH20GK8x1S4Z r++w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=3B7sNafZtBlgHmh5fpLAa14mnyUBnuiEHhgxOSu4EUY=; b=H5ysqQGJuRDIH5nBKd9UGUQzbVrrx3b1XPONajKCf0lMWAOrmKn5sxzwlSjquzNb+i j6HUVAs8F2vBa9uVJE28aWmWjmTIXlV3A6JL5fRDCpCqF4Gaim3SYJJSeeYiPhusbC1N oC9hdvbDSwHkOXhmUmTxgc2/mcLgmLU+49VaDNVkZ+jFGs97cLRNthNAiGzdkLMvDbtU IxQkUkXeOlHOJrZ2/BjUuBxNs+FkYPNTzLksqr5S6vrNqsl2C/KjWmkkEGhL9xKXXa/Z YlRVPs8mn8QLI9rs8omSIW98nsObQMwUSAePN1QB1AnLbv0rUlo0OApG2dSLWAIUsbvV YWpQ== X-Gm-Message-State: AO0yUKUXMOW5eTzuDSDDgVM4okhxBgyHJN6DJpo6cae4h3TRdF8CJUYN dOI8i36Xab0VLsl2cZOdQMgENQ== X-Google-Smtp-Source: AK7set/FrMA+DzzJjfgDbDVBnD4DP8OP+6IttlJ5FihjDu+ykoY0DseCdfCDQOT7VAaqhwcLBAHAYg== X-Received: by 2002:a17:90b:948:b0:236:7f67:8338 with SMTP id dw8-20020a17090b094800b002367f678338mr365975pjb.4.1676884650199; Mon, 20 Feb 2023 01:17:30 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.229]) by smtp.gmail.com with ESMTPSA id fs13-20020a17090af28d00b002339195a47bsm432382pjb.53.2023.02.20.01.17.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Feb 2023 01:17:29 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com Cc: tkhai@ya.ru, 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 5/5] mm: shrinkers: convert shrinker_rwsem to mutex Date: Mon, 20 Feb 2023 17:16:37 +0800 Message-Id: <20230220091637.64865-6-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230220091637.64865-1-zhengqi.arch@bytedance.com> References: <20230220091637.64865-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Now there are no readers of shrinker_rwsem, so we can simply replace it with mutex lock. Signed-off-by: Qi Zheng --- drivers/md/dm-cache-metadata.c | 2 +- drivers/md/dm-thin-metadata.c | 2 +- fs/super.c | 2 +- mm/shrinker_debug.c | 14 +++++++------- mm/vmscan.c | 30 +++++++++++++++--------------- 5 files changed, 25 insertions(+), 25 deletions(-) diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index acffed750e3e..9e0c69958587 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -1828,7 +1828,7 @@ int dm_cache_metadata_abort(struct dm_cache_metadata = *cmd) * Replacement block manager (new_bm) is created and old_bm destroyed out= side of * cmd root_lock to avoid ABBA deadlock that would result (due to life-cy= cle of * shrinker associated with the block manager's bufio client vs cmd root_= lock). - * - must take shrinker_rwsem without holding cmd->root_lock + * - must take shrinker_mutex without holding cmd->root_lock */ new_bm =3D dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZ= E << SECTOR_SHIFT, CACHE_MAX_CONCURRENT_LOCKS); diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c index fd464fb024c3..9f5cb52c5763 100644 --- a/drivers/md/dm-thin-metadata.c +++ b/drivers/md/dm-thin-metadata.c @@ -1887,7 +1887,7 @@ int dm_pool_abort_metadata(struct dm_pool_metadata *p= md) * Replacement block manager (new_bm) is created and old_bm destroyed out= side of * pmd root_lock to avoid ABBA deadlock that would result (due to life-cy= cle of * shrinker associated with the block manager's bufio client vs pmd root_= lock). - * - must take shrinker_rwsem without holding pmd->root_lock + * - must take shrinker_mutex without holding pmd->root_lock */ new_bm =3D dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE <<= SECTOR_SHIFT, THIN_MAX_CONCURRENT_LOCKS); diff --git a/fs/super.c b/fs/super.c index 84332d5cb817..91a4037b1d95 100644 --- a/fs/super.c +++ b/fs/super.c @@ -54,7 +54,7 @@ static char *sb_writers_name[SB_FREEZE_LEVELS] =3D { * One thing we have to be careful of with a per-sb shrinker is that we do= n't * drop the last active reference to the superblock from within the shrink= er. * If that happens we could trigger unregistering the shrinker from within= the - * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we + * shrinker path and that leads to deadlock on the shrinker_mutex. Hence we * take a passive reference to the superblock to avoid this from occurring. */ static unsigned long super_cache_scan(struct shrinker *shrink, diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index 6a26e8ac40aa..4c3a5d9afb5c 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -7,7 +7,7 @@ #include =20 /* defined in vmscan.c */ -extern struct rw_semaphore shrinker_rwsem; +extern struct mutex shrinker_mutex; extern struct list_head shrinker_list; extern struct srcu_struct shrinker_srcu; =20 @@ -167,7 +167,7 @@ int shrinker_debugfs_add(struct shrinker *shrinker) char buf[128]; int id; =20 - lockdep_assert_held(&shrinker_rwsem); + lockdep_assert_held(&shrinker_mutex); =20 /* debugfs isn't initialized yet, add debugfs entries later. */ if (!shrinker_debugfs_root) @@ -210,7 +210,7 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, = const char *fmt, ...) if (!new) return -ENOMEM; =20 - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); =20 old =3D shrinker->name; shrinker->name =3D new; @@ -228,7 +228,7 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, = const char *fmt, ...) shrinker->debugfs_entry =3D entry; } =20 - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); =20 kfree_const(old); =20 @@ -240,7 +240,7 @@ struct dentry *shrinker_debugfs_remove(struct shrinker = *shrinker) { struct dentry *entry =3D shrinker->debugfs_entry; =20 - lockdep_assert_held(&shrinker_rwsem); + lockdep_assert_held(&shrinker_mutex); =20 kfree_const(shrinker->name); shrinker->name =3D NULL; @@ -265,14 +265,14 @@ static int __init shrinker_debugfs_init(void) shrinker_debugfs_root =3D dentry; =20 /* Create debugfs entries for shrinkers registered at boot */ - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); list_for_each_entry(shrinker, &shrinker_list, list) if (!shrinker->debugfs_entry) { ret =3D shrinker_debugfs_add(shrinker); if (ret) break; } - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); =20 return ret; } diff --git a/mm/vmscan.c b/mm/vmscan.c index b8da56beba96..f94bfe540675 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -35,7 +35,7 @@ #include #include #include -#include +#include #include #include #include @@ -202,7 +202,7 @@ static void set_task_reclaim_state(struct task_struct *= task, } =20 LIST_HEAD(shrinker_list); -DECLARE_RWSEM(shrinker_rwsem); +DEFINE_MUTEX(shrinker_mutex); DEFINE_SRCU(shrinker_srcu); =20 #ifdef CONFIG_MEMCG @@ -224,7 +224,7 @@ static struct shrinker_info *shrinker_info_protected(st= ruct mem_cgroup *memcg, { return srcu_dereference_check(memcg->nodeinfo[nid]->shrinker_info, &shrinker_srcu, - lockdep_is_held(&shrinker_rwsem)); + lockdep_is_held(&shrinker_mutex)); } =20 static struct shrinker_info *shrinker_info_srcu(struct mem_cgroup *memcg, @@ -297,7 +297,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) int nid, size, ret =3D 0; int map_size, defer_size =3D 0; =20 - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); map_size =3D shrinker_map_size(shrinker_nr_max); defer_size =3D shrinker_defer_size(shrinker_nr_max); size =3D map_size + defer_size; @@ -312,7 +312,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) info->map =3D (void *)info->nr_deferred + defer_size; rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info); } - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); =20 return ret; } @@ -337,7 +337,7 @@ static int expand_shrinker_info(int new_id) if (!root_mem_cgroup) goto out; =20 - lockdep_assert_held(&shrinker_rwsem); + lockdep_assert_held(&shrinker_mutex); =20 map_size =3D shrinker_map_size(new_nr_max); defer_size =3D shrinker_defer_size(new_nr_max); @@ -384,7 +384,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shr= inker) if (mem_cgroup_disabled()) return -ENOSYS; =20 - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); id =3D idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL); if (id < 0) goto unlock; @@ -398,7 +398,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shr= inker) shrinker->id =3D id; ret =3D 0; unlock: - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); return ret; } =20 @@ -408,7 +408,7 @@ static void unregister_memcg_shrinker(struct shrinker *= shrinker) =20 BUG_ON(id < 0); =20 - lockdep_assert_held(&shrinker_rwsem); + lockdep_assert_held(&shrinker_mutex); =20 idr_remove(&shrinker_idr, id); } @@ -701,9 +701,9 @@ void free_prealloced_shrinker(struct shrinker *shrinker) shrinker->name =3D NULL; #endif if (shrinker->flags & SHRINKER_MEMCG_AWARE) { - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); unregister_memcg_shrinker(shrinker); - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); return; } =20 @@ -713,11 +713,11 @@ void free_prealloced_shrinker(struct shrinker *shrink= er) =20 void register_shrinker_prepared(struct shrinker *shrinker) { - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); list_add_tail_rcu(&shrinker->list, &shrinker_list); shrinker->flags |=3D SHRINKER_REGISTERED; shrinker_debugfs_add(shrinker); - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); } =20 static int __register_shrinker(struct shrinker *shrinker) @@ -767,13 +767,13 @@ void unregister_shrinker(struct shrinker *shrinker) if (!(shrinker->flags & SHRINKER_REGISTERED)) return; =20 - down_write(&shrinker_rwsem); + mutex_lock(&shrinker_mutex); list_del_rcu(&shrinker->list); shrinker->flags &=3D ~SHRINKER_REGISTERED; if (shrinker->flags & SHRINKER_MEMCG_AWARE) unregister_memcg_shrinker(shrinker); debugfs_entry =3D shrinker_debugfs_remove(shrinker); - up_write(&shrinker_rwsem); + mutex_unlock(&shrinker_mutex); =20 synchronize_srcu(&shrinker_srcu); =20 --=20 2.20.1