From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2E20C432C0 for ; Mon, 25 Nov 2019 18:01:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C84C20679 for ; Mon, 25 Nov 2019 18:01:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727594AbfKYSBz (ORCPT ); Mon, 25 Nov 2019 13:01:55 -0500 Received: from mga02.intel.com ([134.134.136.20]:48573 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725823AbfKYSBz (ORCPT ); Mon, 25 Nov 2019 13:01:55 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Nov 2019 10:01:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,242,1571727600"; d="scan'208";a="198548773" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by orsmga007.jf.intel.com with ESMTP; 25 Nov 2019 10:01:36 -0800 Date: Mon, 25 Nov 2019 10:01:36 -0800 From: Sean Christopherson To: Sasha Levin Cc: gregkh@linuxfoundation.org, dan.j.williams@intel.com, david@redhat.com, kilobyte@angband.pl, pbonzini@redhat.com, stable@vger.kernel.org Subject: Re: FAILED: patch "[PATCH] KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved" failed to apply to 4.19-stable tree Message-ID: <20191125180136.GE12178@linux.intel.com> References: <1574090560219@kroah.com> <20191125174359.GI5861@sasha-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191125174359.GI5861@sasha-vm> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Nov 25, 2019 at 12:43:59PM -0500, Sasha Levin wrote: > On Mon, Nov 18, 2019 at 04:22:40PM +0100, gregkh@linuxfoundation.org wrote: > > > >The patch below does not apply to the 4.19-stable tree. > >If someone wants it applied there, or to any other stable or longterm > >tree, then please email the backport, including the original git commit > >id to . > > > >thanks, > > > >greg k-h > > > >------------------ original commit in Linus's tree ------------------ > > > >From a78986aae9b2988f8493f9f65a587ee433e83bc3 Mon Sep 17 00:00:00 2001 > >From: Sean Christopherson > >Date: Mon, 11 Nov 2019 14:12:27 -0800 > >Subject: [PATCH] KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved > > > >Explicitly exempt ZONE_DEVICE pages from kvm_is_reserved_pfn() and > >instead manually handle ZONE_DEVICE on a case-by-case basis. For things > >like page refcounts, KVM needs to treat ZONE_DEVICE pages like normal > >pages, e.g. put pages grabbed via gup(). But for flows such as setting > >A/D bits or shifting refcounts for transparent huge pages, KVM needs to > >to avoid processing ZONE_DEVICE pages as the flows in question lack the > >underlying machinery for proper handling of ZONE_DEVICE pages. > > > >This fixes a hang reported by Adam Borowski[*] in dev_pagemap_cleanup() > >when running a KVM guest backed with /dev/dax memory, as KVM straight up > >doesn't put any references to ZONE_DEVICE pages acquired by gup(). > > > >Note, Dan Williams proposed an alternative solution of doing put_page() > >on ZONE_DEVICE pages immediately after gup() in order to simplify the > >auditing needed to ensure is_zone_device_page() is called if and only if > >the backing device is pinned (via gup()). But that approach would break > >kvm_vcpu_{un}map() as KVM requires the page to be pinned from map() 'til > >unmap() when accessing guest memory, unlike KVM's secondary MMU, which > >coordinates with mmu_notifier invalidations to avoid creating stale > >page references, i.e. doesn't rely on pages being pinned. > > > >[*] http://lkml.kernel.org/r/20190919115547.GA17963@angband.pl > > > >Reported-by: Adam Borowski > >Analyzed-by: David Hildenbrand > >Acked-by: Dan Williams > >Cc: stable@vger.kernel.org > >Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") > >Signed-off-by: Sean Christopherson > >Signed-off-by: Paolo Bonzini > > I also took e7912386ede8 ("KVM: x86: reintroduce pte_list_remove, but > including mmu_spte_clear_track_bits") and queued both for 4.19-4.9. I don't think that will work, you'd also have to pull in commit 8daf346226b2 ("KVM: x86: rename pte_list_remove to __pte_list_remove"). And e7912386ede8 in particular isn't stable material. I'll send a proper backport for 4.19 and earlier, the conflicts should be easy to resolve.