Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933979AbbEOHoX (ORCPT ); Fri, 15 May 2015 03:44:23 -0400 Received: from cantor2.suse.de ([195.135.220.15]:52625 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752934AbbEOHoV (ORCPT ); Fri, 15 May 2015 03:44:21 -0400 Message-ID: <5555A3D1.3010108@suse.cz> Date: Fri, 15 May 2015 09:44:17 +0200 From: Vlastimil Babka User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins CC: Dave Hansen , Mel Gorman , Rik van Riel , Christoph Lameter , Naoya Horiguchi , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , Jerome Marchand , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv5 03/28] memcg: adjust to support new THP refcounting References: <1429823043-157133-1-git-send-email-kirill.shutemov@linux.intel.com> <1429823043-157133-4-git-send-email-kirill.shutemov@linux.intel.com> In-Reply-To: <1429823043-157133-4-git-send-email-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1303 Lines: 29 On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote: > As with rmap, with new refcounting we cannot rely on PageTransHuge() to > check if we need to charge size of huge page form the cgroup. We need to > get information from caller to know whether it was mapped with PMD or > PTE. > > We do uncharge when last reference on the page gone. At that point if we > see PageTransHuge() it means we need to unchange whole huge page. > > The tricky part is partial unmap -- when we try to unmap part of huge > page. We don't do a special handing of this situation, meaning we don't > uncharge the part of huge page unless last user is gone or > split_huge_page() is triggered. In case of cgroup memory pressure > happens the partial unmapped page will be split through shrinker. This > should be good enough. > > Signed-off-by: Kirill A. Shutemov > Tested-by: Sasha Levin Acked-by: Vlastimil Babka But same question about whether it should be using hpage_nr_pages() instead of a constant. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/