From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by kanga.kvack.org (Postfix) with ESMTP id D3B126B0038 for ; Tue, 12 May 2015 06:41:07 -0400 (EDT) Received: by wief7 with SMTP id f7so108595881wie.0 for ; Tue, 12 May 2015 03:41:07 -0700 (PDT) Received: from kirsi1.inet.fi (mta-out1.inet.fi. [62.71.2.227]) by mx.google.com with ESMTP id fu7si2446333wib.72.2015.05.12.03.41.05 for ; Tue, 12 May 2015 03:41:06 -0700 (PDT) Date: Tue, 12 May 2015 13:40:55 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH v2 1/3] pagemap: add mmap-exclusive bit for marking pages mapped only here Message-ID: <20150512104055.GB18365@node.dhcp.inet.fi> References: <20150512090156.24768.2521.stgit@buzz> <20150512094303.24768.10282.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150512094303.24768.10282.stgit@buzz> Sender: owner-linux-mm@kvack.org List-ID: To: Konstantin Khlebnikov Cc: linux-mm@kvack.org, Naoya Horiguchi , linux-kernel@vger.kernel.org, Andrew Morton , Mark Williamson , Pavel Emelyanov , linux-api@vger.kernel.org, Andy Lutomirski , Vlastimil Babka , Pavel Machek , Mark Seaborn , Linus Torvalds , Daniel James , Finn Grimwood On Tue, May 12, 2015 at 12:43:03PM +0300, Konstantin Khlebnikov wrote: > This patch sets bit 56 in pagemap if this page is mapped only once. > It allows to detect exclusively used pages without exposing PFN: > > present file exclusive state > 0 0 0 non-present > 1 1 0 file page mapped somewhere else > 1 1 1 file page mapped only here > 1 0 0 anon non-CoWed page (shared with parent/child) > 1 0 1 anon CoWed page (or never forked) Probably, worth noting that file-private pages are anon in this context. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org