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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id 34si3414770pgt.455.2019.02.14.14.11.59 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 14 Feb 2019 14:11:59 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=ZJoXraRw; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Gwc+mvIl4HoO2YfH2m0A8g4VcbExcOq+aBb16LSf1EI=; b=ZJoXraRwEzPwCjFopYp0D/SBf oExrdMzVb4bcoedsPJXTMRiM0f6llqjnv/ND3gdcr+NN16Gq1xGdvVTqEgNNZX38lB+ajiti5MA5t QoqGD5j8TSkMmRlf164otrER2pPPxdHs7/xFdtYUKvWe1CM2uv2056tV38vrfj980Q8nYSb4qeZPD dF/qOaxvuArkL9sJ76rWgnG0MEcIhoYJk5GtmpFDkCWtXadhb69achm2/Zaps8K9G7VAoZf41Fdk1 x8bAHEI2bXJ9uISExFkUX+h1zUPiovdWqDjpf2mzLfIBkzHpWLKB8hsFRfWmPNqnMb2owjs0KHqog z1ps54Vxg==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1guPEc-0006Mt-7X; Thu, 14 Feb 2019 22:11:58 +0000 Date: Thu, 14 Feb 2019 14:11:58 -0800 From: Matthew Wilcox To: "Kirill A. Shutemov" Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Hugh Dickins , William Kucharski Subject: Re: [PATCH v2] page cache: Store only head pages in i_pages Message-ID: <20190214221158.GF12668@bombadil.infradead.org> References: <20190212183454.26062-1-willy@infradead.org> <20190214133004.js7s42igiqc5pgwf@kshutemo-mobl1> <20190214211757.GE12668@bombadil.infradead.org> <20190214220810.cs2ecomtrqc6m2ap@kshutemo-mobl1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190214220810.cs2ecomtrqc6m2ap@kshutemo-mobl1> User-Agent: Mutt/1.9.2 (2017-12-15) 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 Fri, Feb 15, 2019 at 01:08:10AM +0300, Kirill A. Shutemov wrote: > On Thu, Feb 14, 2019 at 01:17:57PM -0800, Matthew Wilcox wrote: > > On Thu, Feb 14, 2019 at 04:30:04PM +0300, Kirill A. Shutemov wrote: > > > - migrate_page_move_mapping() has to be converted too. > > > > I think that's as simple as: > > > > +++ b/mm/migrate.c > > @@ -465,7 +465,7 @@ int migrate_page_move_mapping(struct address_space *mapping, > > > > for (i = 1; i < HPAGE_PMD_NR; i++) { > > xas_next(&xas); > > - xas_store(&xas, newpage + i); > > + xas_store(&xas, newpage); > > } > > } > > > > > > or do you see something else I missed? > > Looks right to me. > > BTW, maybe some add syntax sugar from XArray side? > > Replace the loop and xas_store() before it with: > > xas_fill(&xas, newpage, 1UL << compound_order(newpage)); > > or something similar? If we were keeping this code longterm, then yes, something like that would be great. I'm hoping this code is a mere stepping stone towards using multi-slot entries for the page cache.