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Date: Fri, 12 Oct 2018 17:08:33 +0200
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: s390: runtime warning about pgtables_bytes
In-Reply-To: <20181011150211.7d8c07ac@mschwideX1>
References: <CAEemH2eExK_jwOPZDFBZkwABucpZqh+=s+qpN-tFfMzxwo7cZA@mail.gmail.com>
	<20181011150211.7d8c07ac@mschwideX1>
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To: Li Wang <liwang@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>, Janosch Frank <frankja@linux.vnet.ibm.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, linux-kernel <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>

On Thu, 11 Oct 2018 15:02:11 +0200
Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> On Thu, 11 Oct 2018 18:04:12 +0800
> Li Wang <liwang@redhat.com> wrote:
>=20
> > When running s390 system with LTP/cve-2017-17052.c[1], the following BU=
G is
> > came out repeatedly.
> > I remember this warning start from kernel-4.16.0 and now it still exist=
 in
> > kernel-4.19-rc7.
> > Can anyone take a look?
> >=20
> > [ 2678.991496] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.001543] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.002453] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.003256] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.013689] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.024647] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.064408] BUG: non-zero pgtables_bytes on freeing mm: 16384
> > [ 2679.133963] BUG: non-zero pgtables_bytes on freeing mm: 16384
> >=20
> > [1]:
> > https://github.com/linux-test-project/ltp/blob/master/testcases/cve/cve=
-2017-17052.c=20=20
>=20=20
> Confirmed, I see this bug with cvs-2017-17052 on my LPAR as well.
> I'll look into it.
=20
Ok, I think I understand the problem now. This is the patch I am testing
right now. It seems to fix the issue, but I had to change common mm
code for it.
--