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Date: Fri, 20 May 2016 08:48:20 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, luto@amacapital.net,
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        akpm@linux-foundation.org, linux-mm@kvack.org, 0x7f454c46@gmail.com,
        Shuah Khan <shuahkh@osg.samsung.com>, linux-kselftest@vger.kernel.org
Subject: Re: [PATCHv9 2/2] selftest/x86: add mremap vdso test
Message-ID: <20160520064820.GB29418@gmail.com>
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* Dmitry Safonov <dsafonov@virtuozzo.com> wrote:

> Should print on success:
> [root@localhost ~]# ./test_mremap_vdso_32
> 	AT_SYSINFO_EHDR is 0xf773f000
> [NOTE]	Moving vDSO: [f773f000, f7740000] -> [a000000, a001000]
> [OK]
> Or segfault if landing was bad (before patches):
> [root@localhost ~]# ./test_mremap_vdso_32
> 	AT_SYSINFO_EHDR is 0xf774f000
> [NOTE]	Moving vDSO: [f774f000, f7750000] -> [a000000, a001000]
> Segmentation fault (core dumped)

So I still think that generating potential segfaults is not a proper way to test a 
new feature. How are we supposed to tell the feature still works? I realize that 
glibc is a problem here - but that doesn't really change the QA equation: we are 
adding new kernel code to help essentially a single application out of tens of 
thousands of applications.

At minimum we should have a robust testcase ...

Thanks,

	Ingo