From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1526800129; cv=none; d=google.com; s=arc-20160816; b=UBuV8qlfZLj3Us8TILK//Gz9S5cANYZDhxBHYMSV9Jsb8ugtGkuquyYF87MbBXVc8/ 6VySab7rZKYgiSlqn9X7gcBnzxWFFmL79dh2AG6y3fmqdI1kMef8QAXs0jWdupdRb02f yaLKLIMPFTMLWHwxr2qZXx+C0pdLVJ6kn6PDyYsoYHopqhZCs7Xqz+hVp70LYFOBETz8 X06F2GyBX0eRXqKYQV7ad9z3Etmeo05gSclrcTA49mziPA4NfssGgRAd7JjPP55H7tGy GPxOc6HuwcwJDPmP0yyShG6tgJAvPD0/h5wEMdyl0Bz2B3t1Flfg5Dg8AORYaRxbV1eh efpg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:dkim-signature:arc-authentication-results; bh=AV+Xm8lWfRJQWRJe+MFO86ST9NxbJSCp4wvcUfVYKE8=; b=nvkehd7drzFIIZg+YrY+zxGqpQWbPvkXgAmc3EzJygVejfVfJF523iai3+K5uMLNvl cj/pzVF1MrGgLNcMAsVN7gINqKmvnZFm8rf9xPC+viTbsdhDcIaU8/h3c140p2ygkA0t d+EeBWrtnUA0iUVts+eXty7FXLl0EDYVRpN072GXLoktdaWXQASdM0CgF02KrIQiFdys /fnd3aa7Z5XUxAFTrgYRtStWDWl1C1a8rTIrBmaLffxQTTPRLpwgnSRTdogh6koRTEmT HrAJU7Q/wLW/b+9Ng5TS17KfFsdL/RI+o28jU1+Fgo1iJPI+wycNa5rBzk2S3AbrV3wq 5Lag== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=jVGrZQ8m; spf=pass (google.com: domain of vdavydov.dev@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=vdavydov.dev@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=jVGrZQ8m; spf=pass (google.com: domain of vdavydov.dev@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=vdavydov.dev@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AB8JxZqqd8c0/KSkiLNDqNQAc37mu/Vz/Pgmr4/QAcP6+w6pFYdyx7S5NpB0tAH5EFNvFRFqEIy6tA== Date: Sun, 20 May 2018 10:08:46 +0300 From: Vladimir Davydov To: Kirill Tkhai Cc: akpm@linux-foundation.org, shakeelb@google.com, viro@zeniv.linux.org.uk, hannes@cmpxchg.org, mhocko@kernel.org, tglx@linutronix.de, pombredanne@nexb.com, stummala@codeaurora.org, gregkh@linuxfoundation.org, sfr@canb.auug.org.au, guro@fb.com, mka@chromium.org, penguin-kernel@I-love.SAKURA.ne.jp, chris@chris-wilson.co.uk, longman@redhat.com, minchan@kernel.org, ying.huang@intel.com, mgorman@techsingularity.net, jbacik@fb.com, linux@roeck-us.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, lirongqing@baidu.com, aryabinin@virtuozzo.com Subject: Re: [PATCH v6 03/17] mm: Assign id to every memcg-aware shrinker Message-ID: <20180520070846.jfgfl23ionghevlw@esperanza> References: <152663268383.5308.8660992135988724014.stgit@localhost.localdomain> <152663292827.5308.15476497557507652648.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <152663292827.5308.15476497557507652648.stgit@localhost.localdomain> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1600790667244060428?= X-GMAIL-MSGID: =?utf-8?q?1600965972849265407?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hello Kirill, Generally, all patches in the series look OK to me, but I'm going to do some nitpicking before I ack them. See below. On Fri, May 18, 2018 at 11:42:08AM +0300, Kirill Tkhai wrote: > The patch introduces shrinker::id number, which is used to enumerate > memcg-aware shrinkers. The number start from 0, and the code tries > to maintain it as small as possible. > > This will be used as to represent a memcg-aware shrinkers in memcg > shrinkers map. > > Since all memcg-aware shrinkers are based on list_lru, which is per-memcg > in case of !CONFIG_MEMCG_KMEM only, the new functionality will be under > this config option. > > Signed-off-by: Kirill Tkhai > --- > include/linux/shrinker.h | 4 +++ > mm/vmscan.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 64 insertions(+) > > diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h > index 6794490f25b2..7ca9c18cf130 100644 > --- a/include/linux/shrinker.h > +++ b/include/linux/shrinker.h > @@ -66,6 +66,10 @@ struct shrinker { > > /* These are for internal use */ > struct list_head list; > +#ifdef CONFIG_MEMCG_KMEM > + /* ID in shrinker_idr */ > + int id; > +#endif > /* objs pending delete, per node */ > atomic_long_t *nr_deferred; > }; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 50055d72f294..3de12a9bdf85 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -169,6 +169,48 @@ unsigned long vm_total_pages; > static LIST_HEAD(shrinker_list); > static DECLARE_RWSEM(shrinker_rwsem); > > +#ifdef CONFIG_MEMCG_KMEM > +static DEFINE_IDR(shrinker_idr); > + > +static int prealloc_memcg_shrinker(struct shrinker *shrinker) > +{ > + int id, ret; > + > + shrinker->id = -1; > + down_write(&shrinker_rwsem); > + ret = id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL); > + if (ret < 0) > + goto unlock; > + shrinker->id = id; > + ret = 0; > +unlock: > + up_write(&shrinker_rwsem); > + return ret; > +} > + > +static void unregister_memcg_shrinker(struct shrinker *shrinker) > +{ > + int id = shrinker->id; > + > + if (id < 0) > + return; Nit: Please replace this with BUG_ON(id >= 0) - this function can only be called for a memcg-aware shrinker that has been fully initialized (prealloc_shrinker() sets nr_deferred after id; unregister_shrinker() returns immediately if nr_deferred is NULL). > + > + down_write(&shrinker_rwsem); > + idr_remove(&shrinker_idr, id); > + up_write(&shrinker_rwsem); > + shrinker->id = -1; Nit: I'd move this under shrinker_rwsem as you set it with the rwsem taken. > +} > +#else /* CONFIG_MEMCG_KMEM */ > +static int prealloc_memcg_shrinker(struct shrinker *shrinker) > +{ > + return 0; > +} > + > +static void unregister_memcg_shrinker(struct shrinker *shrinker) > +{ > +} > +#endif /* CONFIG_MEMCG_KMEM */ > + > #ifdef CONFIG_MEMCG > static bool global_reclaim(struct scan_control *sc) > { > @@ -306,6 +348,7 @@ unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone > int prealloc_shrinker(struct shrinker *shrinker) > { > size_t size = sizeof(*shrinker->nr_deferred); > + int ret; > > if (shrinker->flags & SHRINKER_NUMA_AWARE) > size *= nr_node_ids; > @@ -313,11 +356,26 @@ int prealloc_shrinker(struct shrinker *shrinker) > shrinker->nr_deferred = kzalloc(size, GFP_KERNEL); > if (!shrinker->nr_deferred) > return -ENOMEM; > + > + if (shrinker->flags & SHRINKER_MEMCG_AWARE) { > + ret = prealloc_memcg_shrinker(shrinker); > + if (ret) > + goto free_deferred; Nit: 'ret' is not really needed here. > + } > + > return 0; > + > +free_deferred: > + kfree(shrinker->nr_deferred); > + shrinker->nr_deferred = NULL; > + return -ENOMEM; > } > > void free_prealloced_shrinker(struct shrinker *shrinker) > { > + if (shrinker->flags & SHRINKER_MEMCG_AWARE) > + unregister_memcg_shrinker(shrinker); > + > kfree(shrinker->nr_deferred); > shrinker->nr_deferred = NULL; > } > @@ -347,6 +405,8 @@ void unregister_shrinker(struct shrinker *shrinker) > { > if (!shrinker->nr_deferred) > return; > + if (shrinker->flags & SHRINKER_MEMCG_AWARE) > + unregister_memcg_shrinker(shrinker); > down_write(&shrinker_rwsem); > list_del(&shrinker->list); > up_write(&shrinker_rwsem); >