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received-spf: None (protection.outlook.com: vmware.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: BG9N2f8C+dlo3mBMwuqnPoQzRUmb/nEAM7EVvFo7FSYuYmjPf/rwSEWKGt1rSEYoJEM+9/TjXzYpf6xO4E4LgQAOfJmW3Z2ym7oNYir6Zl+PY1txlEUPTb4Fj1bukSx/5zKWMj7X/3Fq7o/S0hpJj1dU+H7obCquEwS5mSpscKrzqrkUWQL5s0BhE/T8BeePu4SPM2QNlwIGRFbGOyddi1wkvX0bI1OrZzXJORVGjE/AgqijTWuy8dL/8OdsgEGF32TeRnyHbj7QL1Fpg8N0WAzZT/uCCQawzQJlXUmsekv9GtRxxIbCyNsPEwRZrq7POqBHoSgHUawvrzZKSopoNMxQlt0WdcskYBTUUMn8FG6JhP9Ni3SSHTkS1pkqCDuP/c365wKSuWXgHtwc3fIfb1RLljJJ9wur36L7thPqa+Y= Content-Type: text/plain; charset="us-ascii" Content-ID: <50EB2B33C821234E9E7264AB3F0F5A4C@namprd05.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: vmware.com X-MS-Exchange-CrossTenant-Network-Message-Id: f0787024-0a84-4317-c63a-08d6a70fb8ff X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Mar 2019 17:25:28.8020 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR05MB5704 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Mar 12, 2019, at 10:23 AM, David Hildenbrand wrote: >=20 > On 12.03.19 18:14, Matthew Wilcox wrote: >> On Tue, Mar 12, 2019 at 05:05:39PM +0000, Julien Grall wrote: >>> On 3/12/19 3:59 PM, Julien Grall wrote: >>>> It looks like all the arm test for linus [1] and next [2] tree >>>> are now failing. x86 seems to be mostly ok. >>>>=20 >>>> The bisector fingered the following commit: >>>>=20 >>>> commit 0ee930e6cafa048c1925893d0ca89918b2814f2c >>>> Author: Matthew Wilcox >>>> Date: Tue Mar 5 15:46:06 2019 -0800 >>>>=20 >>>> mm/memory.c: prevent mapping typed pages to userspace >>>> Pages which use page_type must never be mapped to userspace as it = would >>>> destroy their page type. Add an explicit check for this instead o= f >>>> assuming that kernel drivers always get this right. >>=20 >> Oh good, it found a real problem. >>=20 >>> It turns out the problem is because the balloon driver will call >>> __SetPageOffline() on allocated page. Therefore the page has a type and >>> vm_insert_pages will deny the insertion. >>>=20 >>> My knowledge is quite limited in this area. So I am not sure how we can >>> solve the problem. >>>=20 >>> I would appreciate if someone could provide input of to fix the mapping= . >>=20 >> I don't know the balloon driver, so I don't know why it was doing this, >> but what it was doing was Wrong and has been since 2014 with: >=20 > Just to clarify on that point, XEN balloon does not use balloon > compaction as far as I know (only virtio-balloon and as far as I know > now also vmware balloon). Both of them don't map any such pages to user > space, so it never was and isn't a problem. I still need to submit the next version of the patches, but yes, we are not about to map them to userspace (dah).