From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f172.google.com (mail-lb0-f172.google.com [209.85.217.172]) by kanga.kvack.org (Postfix) with ESMTP id 59DBE280257 for ; Tue, 14 Jul 2015 16:15:44 -0400 (EDT) Received: by lbbzr7 with SMTP id zr7so12840358lbb.1 for ; Tue, 14 Jul 2015 13:15:43 -0700 (PDT) Received: from mail-lb0-x229.google.com (mail-lb0-x229.google.com. [2a00:1450:4010:c04::229]) by mx.google.com with ESMTPS id cv1si1922892lbb.49.2015.07.14.13.15.42 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Jul 2015 13:15:42 -0700 (PDT) Received: by lbbyj8 with SMTP id yj8so12835625lbb.0 for ; Tue, 14 Jul 2015 13:15:42 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20150714115252.8f21cfa864935a4b403c3d8d@linux-foundation.org> References: <20150714152516.29844.69929.stgit@buzz> <20150714115252.8f21cfa864935a4b403c3d8d@linux-foundation.org> Date: Tue, 14 Jul 2015 23:15:41 +0300 Message-ID: Subject: Re: [PATCHSET v4 0/5] pagemap: make useable for non-privilege users From: Konstantin Khlebnikov Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Konstantin Khlebnikov , "linux-mm@kvack.org" , Naoya Horiguchi , "Kirill A. Shutemov" , Mark Williamson , Linux Kernel Mailing List , Linux API On Tue, Jul 14, 2015 at 9:52 PM, Andrew Morton wrote: > On Tue, 14 Jul 2015 18:37:34 +0300 Konstantin Khlebnikov wrote: > >> This patchset makes pagemap useable again in the safe way (after row hammer >> bug it was made CAP_SYS_ADMIN-only). This patchset restores access for >> non-privileged users but hides PFNs from them. > > Documentation/vm/pagemap.txt hasn't been updated to describe these > privilege issues? Will do. Too much time passed between versions, I planned but forgot about that. > >> Also it adds bit 'map-exlusive' which is set if page is mapped only here: >> it helps in estimation of working set without exposing pfns and allows to >> distinguish CoWed and non-CoWed private anonymous pages. >> >> Second patch removes page-shift bits and completes migration to the new >> pagemap format: flags soft-dirty and mmap-exlusive are available only >> in the new format. > > I'm not really seeing a description of the new format in these > changelogs. Precisely what got removed, what got added and which > capabilities change the output in what manner? Now pfn (bits 0-54) is zero if task who opened pagemap has no CAP_SYS_ADMIN (system-wide). in v2 format page-shift (bits 55-60) now used for flags: 55 - soft-dirty (added for checkpoint-restore, I guess) 56 - mmap-exclusive (added in last patch) 57-60 - free for use I'll document the history of these changes. > > > -- > 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 -- 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