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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59E5BC433E0 for ; Thu, 28 Jan 2021 17:56:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B497B64E15 for ; Thu, 28 Jan 2021 17:56:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B497B64E15 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D7E916B0005; Thu, 28 Jan 2021 12:56:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D082D6B0006; Thu, 28 Jan 2021 12:56:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BA82C6B006C; Thu, 28 Jan 2021 12:56:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0240.hostedemail.com [216.40.44.240]) by kanga.kvack.org (Postfix) with ESMTP id A13B26B0005 for ; Thu, 28 Jan 2021 12:56:17 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 4A0903621 for ; Thu, 28 Jan 2021 17:56:17 +0000 (UTC) X-FDA: 77755937994.12.cast42_05054f2275a1 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 267FC18006FB0 for ; Thu, 28 Jan 2021 17:56:17 +0000 (UTC) X-HE-Tag: cast42_05054f2275a1 X-Filterd-Recvd-Size: 5593 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Jan 2021 17:56:16 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D8B20ACF4; Thu, 28 Jan 2021 17:56:14 +0000 (UTC) Subject: Re: [v5 PATCH 06/11] mm: vmscan: use a new flag to indicate shrinker is registered To: Yang Shi , guro@fb.com, ktkhai@virtuozzo.com, shakeelb@google.com, david@fromorbit.com, hannes@cmpxchg.org, mhocko@suse.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210127233345.339910-1-shy828301@gmail.com> <20210127233345.339910-7-shy828301@gmail.com> From: Vlastimil Babka Message-ID: Date: Thu, 28 Jan 2021 18:56:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210127233345.339910-7-shy828301@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/28/21 12:33 AM, Yang Shi wrote: > Currently registered shrinker is indicated by non-NULL shrinker->nr_deferred. > This approach is fine with nr_deferred at the shrinker level, but the following > patches will move MEMCG_AWARE shrinkers' nr_deferred to memcg level, so their > shrinker->nr_deferred would always be NULL. This would prevent the shrinkers > from unregistering correctly. > > Remove SHRINKER_REGISTERING since we could check if shrinker is registered > successfully by the new flag. > > Signed-off-by: Yang Shi > --- > include/linux/shrinker.h | 7 ++++--- > mm/vmscan.c | 27 +++++++++------------------ > 2 files changed, 13 insertions(+), 21 deletions(-) > > diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h > index 0f80123650e2..1eac79ce57d4 100644 > --- a/include/linux/shrinker.h > +++ b/include/linux/shrinker.h > @@ -79,13 +79,14 @@ struct shrinker { > #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ > > /* Flags */ > -#define SHRINKER_NUMA_AWARE (1 << 0) > -#define SHRINKER_MEMCG_AWARE (1 << 1) > +#define SHRINKER_REGISTERED (1 << 0) > +#define SHRINKER_NUMA_AWARE (1 << 1) > +#define SHRINKER_MEMCG_AWARE (1 << 2) > /* > * It just makes sense when the shrinker is also MEMCG_AWARE for now, > * non-MEMCG_AWARE shrinker should not have this flag set. > */ > -#define SHRINKER_NONSLAB (1 << 2) > +#define SHRINKER_NONSLAB (1 << 3) > > extern int prealloc_shrinker(struct shrinker *shrinker); > extern void register_shrinker_prepared(struct shrinker *shrinker); > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 92e917033797..256896d157d4 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -308,19 +308,6 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id) > } > } > > -/* > - * We allow subsystems to populate their shrinker-related > - * LRU lists before register_shrinker_prepared() is called > - * for the shrinker, since we don't want to impose > - * restrictions on their internal registration order. > - * In this case shrink_slab_memcg() may find corresponding > - * bit is set in the shrinkers map. > - * > - * This value is used by the function to detect registering > - * shrinkers and to skip do_shrink_slab() calls for them. > - */ > -#define SHRINKER_REGISTERING ((struct shrinker *)~0UL) > - > static DEFINE_IDR(shrinker_idr); > > static int prealloc_memcg_shrinker(struct shrinker *shrinker) > @@ -329,7 +316,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) > > down_write(&shrinker_rwsem); > /* This may call shrinker, so it must use down_read_trylock() */ > - id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL); > + id = idr_alloc(&shrinker_idr, NULL, 0, 0, GFP_KERNEL); Is it still needed to register a NULL and then replace it with real pointer, given the SHRINKER_REGISTERED flag? > if (id < 0) > goto unlock; > > @@ -496,6 +483,7 @@ void register_shrinker_prepared(struct shrinker *shrinker) > if (shrinker->flags & SHRINKER_MEMCG_AWARE) > idr_replace(&shrinker_idr, shrinker, shrinker->id); > #endif > + shrinker->flags |= SHRINKER_REGISTERED; > up_write(&shrinker_rwsem); > } > > @@ -515,13 +503,16 @@ EXPORT_SYMBOL(register_shrinker); > */ > void unregister_shrinker(struct shrinker *shrinker) > { > - if (!shrinker->nr_deferred) > + if (!(shrinker->flags & SHRINKER_REGISTERED)) > return; > - if (shrinker->flags & SHRINKER_MEMCG_AWARE) > - unregister_memcg_shrinker(shrinker); > + > down_write(&shrinker_rwsem); > list_del(&shrinker->list); > + shrinker->flags &= ~SHRINKER_REGISTERED; > up_write(&shrinker_rwsem); > + > + if (shrinker->flags & SHRINKER_MEMCG_AWARE) > + unregister_memcg_shrinker(shrinker); > kfree(shrinker->nr_deferred); > shrinker->nr_deferred = NULL; > } > @@ -687,7 +678,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, > struct shrinker *shrinker; > > shrinker = idr_find(&shrinker_idr, i); > - if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) { > + if (unlikely(!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))) { > if (!shrinker) > clear_bit(i, info->map); > continue; >