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[216.228.121.65]) by mx.google.com with ESMTPS id w193si11385202ywa.205.2019.02.28.13.44.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Feb 2019 13:44:42 -0800 (PST) Received-SPF: pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.65 as permitted sender) client-ip=216.228.121.65; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=ETgESkeO; spf=pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.65 as permitted sender) smtp.mailfrom=jhubbard@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 28 Feb 2019 13:44:40 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 28 Feb 2019 13:44:41 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 28 Feb 2019 13:44:41 -0800 Received: from [10.110.48.28] (172.20.13.39) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 28 Feb 2019 21:44:40 +0000 Subject: Re: [PATCH v2 2/4] mm: remove zone_lru_lock() function access ->lru_lock directly To: Andrey Ryabinin , Andrew Morton CC: Johannes Weiner , Vlastimil Babka , Rik van Riel , , , Michal Hocko , Mel Gorman References: <20190228083329.31892-1-aryabinin@virtuozzo.com> <20190228083329.31892-2-aryabinin@virtuozzo.com> X-Nvconfidentiality: public From: John Hubbard Message-ID: <44ffadb4-4235-76c9-332f-680dda5da521@nvidia.com> Date: Thu, 28 Feb 2019 13:44:40 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190228083329.31892-2-aryabinin@virtuozzo.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8" Content-Language: en-US-large Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1551390281; bh=/Ts67cHhYbVtBZ+ouZr6ycKx2Tx7Wf5W6XYUebOwjOQ=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=ETgESkeOLXCBUzBcNfOUO2yf+ijNCGe+fZc6VGzbXmaEJMlKUxLOKLvNYV5/8cz1j dYxenWULRy+AssayFNv3D//xaKCOnR2vzfzXVEihgonFCN036ihbMkZllx837L2Chn EEB8/qCmpJ5vb9oLVdNJrzdntYZ0nkxxIkfN+IxlGycz7Mv66tyRTZqJPJmUpRH0T0 PISjgmTE9DXqSEgI0XkdQjmdJcM3G8oZsPHv+TccevKPMvh5/nAA28pOLyBMB1JcKi 8C9xvzhZlU9OrJ5Ufe7Hf4bwOK6LZ8nX5lp26h99tC/qUaI5fbJlXXWY4RwM8zFiF+ Rf1UOK82I4Mrg== 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 2/28/19 12:33 AM, Andrey Ryabinin wrote: > We have common pattern to access lru_lock from a page pointer: > zone_lru_lock(page_zone(page)) > > Which is silly, because it unfolds to this: > &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock > while we can simply do > &NODE_DATA(page_to_nid(page))->lru_lock > Hi Andrey, Nice. I like it so much that I immediately want to tweak it. :) > Remove zone_lru_lock() function, since it's only complicate things. > Use 'page_pgdat(page)->lru_lock' pattern instead. Here, I think the zone_lru_lock() is actually a nice way to add a touch of clarity at the call sites. How about, see below: [snip] > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 2fd4247262e9..22423763c0bd 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -788,10 +788,6 @@ typedef struct pglist_data { > > #define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn) > #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid)) > -static inline spinlock_t *zone_lru_lock(struct zone *zone) > -{ > - return &zone->zone_pgdat->lru_lock; > -} > Instead of removing that function, let's change it, and add another (since you have two cases: either a page* or a pgdat* is available), and move it to where it can compile, like this: diff --git a/include/linux/mm.h b/include/linux/mm.h index 80bb6408fe73..cea3437f5d68 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1167,6 +1167,16 @@ static inline pg_data_t *page_pgdat(const struct page *page) return NODE_DATA(page_to_nid(page)); } +static inline spinlock_t *zone_lru_lock(pg_data_t *pgdat) +{ + return &pgdat->lru_lock; +} + +static inline spinlock_t *zone_lru_lock_from_page(struct page *page) +{ + return zone_lru_lock(page_pgdat(page)); +} + #ifdef SECTION_IN_PAGE_FLAGS static inline void set_page_section(struct page *page, unsigned long section) { diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 842f9189537b..e03042fe1d88 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -728,11 +728,6 @@ typedef struct pglist_data { #define node_start_pfn(nid) (NODE_DATA(nid)->node_start_pfn) #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid)) -static inline spinlock_t *zone_lru_lock(struct zone *zone) -{ - return &zone->zone_pgdat->lru_lock; -} - static inline struct lruvec *node_lruvec(struct pglist_data *pgdat) { return &pgdat->lruvec; Like it? thanks, -- John Hubbard NVIDIA