Date: Thu, 23 Jul 2015 11:17:07 -0400
From: Eric B Munson <emunson@akamai.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Davidlohr Bueso <dave@stgolabs.net>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        David Rientjes <rientjes@google.com>, Hugh Dickins <hughd@google.com>,
        Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>,
        Hillf Danton <hillf.zj@alibaba-inc.com>,
        Christoph Hellwig <hch@infradead.org>, Michal Hocko <mhocko@suse.cz>,
        emunson@mgebm.net
Subject: Re: [PATCH v4 00/10] hugetlbfs: add fallocate support
Message-ID: <20150723151707.GB7795@akamai.com>
References: <1437502184-14269-1-git-send-email-mike.kravetz@oracle.com>
 <20150722150647.2597c7e5be9ee1eecc438b6f@linux-foundation.org>
 <1437603594.3298.5.camel@stgolabs.net>
 <20150722153023.e8f15eb4e490f79cc029c8cd@linux-foundation.org>
 <55B024C6.8010504@oracle.com>
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On Wed, 22 Jul 2015, Mike Kravetz wrote:

> On 07/22/2015 03:30 PM, Andrew Morton wrote:
> >On Wed, 22 Jul 2015 15:19:54 -0700 Davidlohr Bueso <dave@stgolabs.net> w=
rote:
> >
> >>>
> >>>I didn't know that libhugetlbfs has tests.  I wonder if that makes
> >>>tools/testing/selftests/vm's hugetlbfstest harmful?
> >>
> >>Why harmful? Redundant, maybe(?).
> >
> >The presence of the in-kernel tests will cause people to add stuff to
> >them when it would be better if they were to apply that effort to
> >making libhugetlbfs better.  Or vice versa.
> >
> >Mike's work is an example.  Someone later makes a change to hugetlbfs, r=
uns
> >the kernel selftest and says "yay, everything works", unaware that they
> >just broke fallocate support.
> >
> >>Does anyone even use selftests for
> >>hugetlbfs regression testing? Lets see, we also have these:
> >>
> >>- hugepage-{mmap,shm}.c
> >>- map_hugetlb.c
> >>
> >>There's probably a lot of room for improvement here.
> >
> >selftests is a pretty scrappy place.  It's partly a dumping ground for
> >things so useful test code doesn't just get lost and bitrotted.  Partly
> >a framework so people who add features can easily test them. Partly to
> >provide tools to architecture maintainers when they wire up new
> >syscalls and the like.
> >
> >Unless there's some good reason to retain the hugetlb part of
> >selftests, I'm thinking we should just remove it to avoid
> >distracting/misleading people.  Or possibly move the libhugetlbfs test
> >code into the kernel tree and maintain it there.
>=20
> Adding Eric as he is the libhugetlbfs maintainer.
>=20
> I think removing the hugetlb selftests in the kernel and pointing
> people to libhugetlbfs is the way to go.  From a very quick scan
> of the selftests, I would guess libhugetlbfs covers everything
> in those tests.
>=20
> I'm willing to verify the testing provided by selftests is included
> in libhugetlbfs, and remove selftests if that is the direction we
> want to take.

I would rather see the test suite stay in the library, there are a
number of tests that rely on infrastructure in the library that is not
available in selftests.

I am happy to help with any tests that need to be added/modified in the
library to cover.


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