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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id bc7si6453200plb.120.2019.02.15.12.28.59 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 15 Feb 2019 12:28:59 -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=W1EkMPd+; 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=RfJTwQxNtAt3SGNUAeeBsgYvXmANCdHsJDtsXuMeyS8=; b=W1EkMPd+0mkWguf2uAGeMdTk3 kZDkDxRdVsxC4bMDWDO/dB6wLusOvD4FSMkOajm/mzZCMr4eRc0QdIhOitulAZ0i+XxsGbICEUzsF 8SYRg2eBxldECz8EjvYHs3DIHmiyAhMqr0ZayB0sutHedapn1CnACbAus6JToj2ZUdkN0IzzpLGVY +L5Z5Ey2VLTT0jd3j/yIAV/AZosDGDfaYDWucu78zkdEFazU32lalN2iDO60DNBh5wAIeL6nYJFsT jmPMJNvC5jyogYRq8H+ygQwIeambm5Myf3CiPc9VDy8QroKcuf+hLTzR2FwjC4hEs3PbAVsoIXG1G a1xMriBPg==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1guk6U-0001Xm-AK; Fri, 15 Feb 2019 20:28:58 +0000 Date: Fri, 15 Feb 2019 12:28:58 -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: <20190215202858.GL12668@bombadil.infradead.org> References: <20190212183454.26062-1-willy@infradead.org> <20190214133004.js7s42igiqc5pgwf@kshutemo-mobl1> <20190214222944.74ipvbnvo2lvfgnr@kshutemo-mobl1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190214222944.74ipvbnvo2lvfgnr@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 01:29:44AM +0300, Kirill A. Shutemov wrote: > On Thu, Feb 14, 2019 at 04:30:04PM +0300, Kirill A. Shutemov wrote: > > On Tue, Feb 12, 2019 at 10:34:54AM -0800, Matthew Wilcox wrote: > > > Transparent Huge Pages are currently stored in i_pages as pointers to > > > consecutive subpages. This patch changes that to storing consecutive > > > pointers to the head page in preparation for storing huge pages more > > > efficiently in i_pages. > > > > > > Large parts of this are "inspired" by Kirill's patch > > > https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@linux.intel.com/ > > > > > > Signed-off-by: Matthew Wilcox > > > > I believe I found few missing pieces: > > > > - page_cache_delete_batch() will blow up on > > > > VM_BUG_ON_PAGE(page->index + HPAGE_PMD_NR - tail_pages > > != pvec->pages[i]->index, page); > > > > - migrate_page_move_mapping() has to be converted too. > > Other missing pieces are memfd_wait_for_pins() and memfd_tag_pins() > We need to call page_mapcount() for tail pages there. @@ -39,6 +39,7 @@ static void memfd_tag_pins(struct xa_state *xas) xas_for_each(xas, page, ULONG_MAX) { if (xa_is_value(page)) continue; + page = find_subpage(page, xas.xa_index); if (page_count(page) - page_mapcount(page) > 1) xas_set_mark(xas, MEMFD_TAG_PINNED); @@ -88,6 +89,7 @@ static int memfd_wait_for_pins(struct address_space *mapping) bool clear = true; if (xa_is_value(page)) continue; + page = find_subpage(page, xas.xa_index); if (page_count(page) - page_mapcount(page) != 1) { /* * On the last scan, we clean up all those tags