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17 Jul 2020 09:59:55 +0000 Received: from EX13MTAUEA002.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan2.iad.amazon.com [10.40.159.162]) by email-inbound-relay-1e-97fdccfd.us-east-1.amazon.com (Postfix) with ESMTPS id 52A8CA11D6; Fri, 17 Jul 2020 09:59:45 +0000 (UTC) Received: from EX13D31EUA004.ant.amazon.com (10.43.165.161) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 17 Jul 2020 09:59:44 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.160.26) by EX13D31EUA004.ant.amazon.com (10.43.165.161) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 17 Jul 2020 09:59:26 +0000 From: SeongJae Park To: SeongJae Park CC: Mike Rapoport , , "SeongJae Park" , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: Re: Re: Re: [PATCH v18 01/14] mm/page_ext: Export lookup_page_ext() to GPL modules Date: Fri, 17 Jul 2020 11:59:10 +0200 Message-ID: <20200717095910.23550-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200713173805.31923-1-sjpark@amazon.com> (raw) MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.160.26] X-ClientProxiedBy: EX13D14UWC003.ant.amazon.com (10.43.162.19) To EX13D31EUA004.ant.amazon.com (10.43.165.161) X-Rspamd-Queue-Id: E82B41808C246 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 Mon, 13 Jul 2020 19:38:05 +0200 SeongJae Park wrote: > On Mon, 13 Jul 2020 20:19:09 +0300 Mike Rapoport wrote: > > > On Mon, Jul 13, 2020 at 02:21:43PM +0200, SeongJae Park wrote: > > > On Mon, 13 Jul 2020 15:08:42 +0300 Mike Rapoport wrote: > > > > > > > Hi, > > > > > > > > On Mon, Jul 13, 2020 at 10:41:31AM +0200, SeongJae Park wrote: > > > > > From: SeongJae Park > > > > > > > > > > This commit exports 'lookup_page_ext()' to GPL modules. It will be used > > > > > by DAMON in following commit for the implementation of the region based > > > > > sampling. > > > > > > > > Maybe I'm missing something, but why is DAMON a module? > > > > > > I made it loadable just for easier adoption from downstream kernels. I could > > > drop the module build support if asked. > > > > Well, exporting core mm symbols to modules should be considred very > > carefully. > > Agreed. I will drop the module support from the next spin. > > > > > Why lookup_page_ext() is required for DAMON? It is not used anywhere in > > this patchset. > > It's indirectly used. In the 6th patch, DAMON uses 'set_page_young()' to not > interfere with other PTE Accessed bit users. And, 'set_page_young()' uses > 'lookup_page_ext()' if !CONFIG_64BIT. That's why I exported it. This also means that it would make no sense if !64BIT && !PAGE_EXTENSION. In the next spin, I will update the DAMON Kconfig to select PAGE_EXTENSION if !64BIT, as same to that of IDLE_PAGE_TRACKING. Thanks, SeongJae Park