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x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=gmail.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752246AbeBFJsa (ORCPT ); Tue, 6 Feb 2018 04:48:30 -0500 Received: from mail-pf0-f195.google.com ([209.85.192.195]:37469 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752187AbeBFJs2 (ORCPT ); Tue, 6 Feb 2018 04:48:28 -0500 X-Google-Smtp-Source: AH8x2276xsm3TWO4wVUs72qIU6b5hVfRkQ9GedaYnjtf6EaCuSPZPMlkuw6/ConHSd0ezvRtZUO1UQ== Date: Tue, 6 Feb 2018 18:48:22 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: "Huang, Ying" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk , Dan Streetman , Seth Jennings , Tetsuo Handa , Shaohua Li , Michal Hocko , Johannes Weiner , Mel Gorman , Shakeel Butt , stable@vger.kernel.org, Sergey Senozhatsky Subject: Re: [PATCH -mm] mm, swap, frontswap: Fix THP swap if frontswap enabled Message-ID: <20180206094822.GA2265@jagdpanzerIV> References: <20180206065404.18815-1-ying.huang@intel.com> <20180206083101.GA17082@eng-minchan1.roam.corp.google.com> <871shy3421.fsf@yhuang-dev.intel.com> <20180206090244.GA20545@eng-minchan1.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180206090244.GA20545@eng-minchan1.roam.corp.google.com> User-Agent: Mutt/1.9.3 (2018-01-21) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hello, On (02/06/18 01:02), Minchan Kim wrote: [..] > Can't we simple do like that if you want to make it simple and rely on someone > who makes frontswap THP-aware later? > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 42fe5653814a..4bf1725407aa 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -934,7 +934,11 @@ int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[]) > > /* Only single cluster request supported */ > WARN_ON_ONCE(n_goal > 1 && cluster); > +#ifdef CONFIG_FRONTSWAP Wouldn't #ifdef CONFIG_THP_SWAP be better? frontswap_enabled() is 'false' on CONFIG_FRONTSWAP configs, should be compiled out anyway. > + /* Now, frontswap doesn't support THP page */ > + if (frontswap_enabled() && cluster) > + return; > +#endif > avail_pgs = atomic_long_read(&nr_swap_pages) / nr_pages; > if (avail_pgs <= 0) > goto noswap; Looks interesting. Technically, can be done earlier - in get_swap_page(), can't it? get_swap_page() has the PageTransHuge(page) && CONFIG_THP_SWAP condition checks. Can add frontswap dependency there. Something like if (PageTransHuge(page)) { if (IS_ENABLED(CONFIG_THP_SWAP)) + if (!frontswap_enabled()) get_swap_pages(1, true, &entry); return entry; } -ss