Received-SPF: pass (google.com: domain of linux-kernel+bounces-22955-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Content-Type: text/plain;
	charset=us-ascii
Precedence: bulk
Mime-Version: 1.0
Subject: Re: [PATCH 1/1] selftests: mm: hugepage-vmemmap fails on 64K page
 size systems.
From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <20240110075351.f4b6f43e31629ddcb96503cc@linux-foundation.org>
Date: Thu, 11 Jan 2024 10:07:58 +0800
Cc: linux-kselftest@vger.kernel.org,
 Aneesh Kumar <aneesh.kumar@linux.ibm.com>,
 Linux-MM <linux-mm@kvack.org>,
 linuxppc-dev@lists.ozlabs.org,
 LKML <linux-kernel@vger.kernel.org>,
 Geetika Moolchandani <geetika@linux.ibm.com>
Content-Transfer-Encoding: quoted-printable
Message-Id: <C3CE35A3-7663-4B8E-9E85-8F0C3CD7D9EC@linux.dev>
References: <3b3a3ae37ba21218481c482a872bbf7526031600.1704865754.git.donettom@linux.vnet.ibm.com>
 <20240110075351.f4b6f43e31629ddcb96503cc@linux-foundation.org>
To: Donet Tom <donettom@linux.vnet.ibm.com>,
 Andrew Morton <akpm@linux-foundation.org>


> On Jan 10, 2024, at 23:53, Andrew Morton <akpm@linux-foundation.org> =
wrote:
>=20
> (cc Muchun)
> On Wed, 10 Jan 2024 14:03:35 +0530 Donet Tom =
<donettom@linux.vnet.ibm.com> wrote:
>=20
>> The kernel sefltest mm/hugepage-vmemmap fails on architectures
>> which has different page size other than 4K. In hugepage-vmemmap
>> page size used is 4k so the pfn calculation will go wrong on systems
>> which has different page size .The length of MAP_HUGETLB memory must
>> be hugepage aligned but in hugepage-vmemmap map length is 2M so this
>> will not get aligned if the system has differnet hugepage size.
>>=20
>> Added  psize() to get the page size and default_huge_page_size() to
>> get the default hugepage size at run time, hugepage-vmemmap test pass
>> on powerpc with 64K page size and x86 with 4K page size.
>>=20
>> Result on powerpc without patch (page size 64K)
>> *# ./hugepage-vmemmap
>> Returned address is 0x7effff000000 whose pfn is 0
>> Head page flags (100000000) is invalid
>> check_page_flags: Invalid argument
>> *#
>>=20
>> Result on powerpc with patch (page size 64K)
>> *# ./hugepage-vmemmap
>> Returned address is 0x7effff000000 whose pfn is 600
>> *#
>>=20
>> Result on x86 with patch (page size 4K)
>> *# ./hugepage-vmemmap
>> Returned address is 0x7fc7c2c00000 whose pfn is 1dac00
>> *#
>>=20
>> Signed-off-by: Donet Tom <donettom@linux.vnet.ibm.com>
>> Reported-by : Geetika Moolchandani (geetika@linux.ibm.com)
>> Tested-by : Geetika Moolchandani (geetika@linux.ibm.com)

Acked-by: Muchun Song <muchun.song@linux.dev>

>=20
> I'll add=20
>=20
> Fixes: b147c89cd429 ("selftests: vm: add a hugetlb test case")
> Cc: <stable@vger.kernel.org>

Yes. It should be a real bug fix.

Thanks.