From: Matthew Wilcox <willy@infradead.org>
To: Julien Grall <julien.grall@arm.com>
Cc: osstest service owner <osstest-admin@xenproject.org>,
xen-devel@lists.xenproject.org, Juergen Gross <jgross@suse.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
david@redhat.com, k.khlebnikov@samsung.com,
Julien Freche <jfreche@vmware.com>, Nadav Amit <namit@vmware.com>,
"VMware, Inc." <pv-drivers@vmware.com>,
linux-mm@kvack.org
Subject: Re: xen: Can't insert balloon page into VM userspace (WAS Re: [Xen-devel] [linux-linus bisection] complete test-arm64-arm64-xl-xsm)
Date: Tue, 12 Mar 2019 10:14:21 -0700 [thread overview]
Message-ID: <20190312171421.GJ19508@bombadil.infradead.org> (raw)
In-Reply-To: <46118631-61d4-adb6-6ffc-4e7c62ea3da9@arm.com>
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.
> >
> > The bisector fingered the following commit:
> >
> > commit 0ee930e6cafa048c1925893d0ca89918b2814f2c
> > Author: Matthew Wilcox <willy@infradead.org>
> > Date: Tue Mar 5 15:46:06 2019 -0800
> >
> > 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 of
> > assuming that kernel drivers always get this right.
Oh good, it found a real problem.
> 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.
>
> My knowledge is quite limited in this area. So I am not sure how we can
> solve the problem.
>
> I would appreciate if someone could provide input of to fix the mapping.
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:
commit d6d86c0a7f8ddc5b38cf089222cb1d9540762dc2
Author: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Date: Thu Oct 9 15:29:27 2014 -0700
mm/balloon_compaction: redesign ballooned pages management
If ballooned pages are supposed to be mapped into userspace, you can't mark
them as ballooned pages using the mapcount field.
next prev parent reply other threads:[~2019-03-12 17:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1h3Uiq-0002L6-Ij@osstest.test-lab.xenproject.org>
[not found] ` <80211e70-5f54-9421-8e8f-2a4fc758ce39@arm.com>
2019-03-12 17:05 ` xen: Can't insert balloon page into VM userspace (WAS Re: [Xen-devel] [linux-linus bisection] complete test-arm64-arm64-xl-xsm) Julien Grall
2019-03-12 17:14 ` Matthew Wilcox [this message]
2019-03-12 17:18 ` David Hildenbrand
2019-03-12 17:24 ` [Xen-devel] xen: Can't insert balloon page into VM userspace (WAS " Andrew Cooper
2019-03-12 18:02 ` Boris Ostrovsky
2019-03-12 18:11 ` Andrew Cooper
2019-03-12 18:23 ` David Hildenbrand
2019-03-12 19:46 ` David Hildenbrand
2019-03-14 8:37 ` Juergen Gross
2019-03-14 14:12 ` Julien Grall
2019-03-14 14:14 ` David Hildenbrand
2019-03-14 14:15 ` Juergen Gross
2019-03-14 14:16 ` David Hildenbrand
2019-03-12 17:39 ` xen: Can't insert balloon page into VM userspace (WAS Re: [Xen-devel] " Julien Grall
2019-03-12 17:49 ` David Hildenbrand
2019-03-12 17:23 ` David Hildenbrand
2019-03-12 17:25 ` Nadav Amit
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