linux-kernel - Re: [PATCH] selftests/vm: Add a test for MAP_FIXED

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Message-ID: <87va62lpbr.fsf@concordia.ellerman.id.au>
Date:   Tue, 16 Oct 2018 11:15:04 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        jannh@...gle.com, linux-mm@...ck.org, khalid.aziz@...cle.com,
        aarcange@...hat.com, fweimer@...hat.com, jhubbard@...dia.com,
        willy@...radead.org, abdhalee@...ux.vnet.ibm.com, joel@....id.au,
        keescook@...omium.org, jasone@...gle.com,
        davidtgoldblatt@...il.com, trasz@...ebsd.org, danielmicay@...il.com
Subject: Re: [PATCH] selftests/vm: Add a test for MAP_FIXED_NOREPLACE

Michal Hocko <mhocko@...nel.org> writes:

> On Sun 14-10-18 00:39:29, Michael Ellerman wrote:
>> Add a test for MAP_FIXED_NOREPLACE, based on some code originally by
>> Jann Horn. This would have caught the overlap bug reported by Daniel Micay.
>> 
>> I originally suggested to Michal that we create MAP_FIXED_NOREPLACE, but
>> instead of writing a selftest I spent my time bike-shedding whether it
>> should be called MAP_FIXED_SAFE/NOCLOBBER/WEAK/NEW .. mea culpa.
>
> You wer one of those to provide a useful feedback actually. So no reason
> to feel sorry. I should have been forced to write a test case instead.
> No idea why I haven't considered that myself actually. So I steal your
> culpa here.

Haha, plenty of culpa to go around :)

Yeah we should try to always have selftests for new flags and things
like this.

This one was a bit special because the original point of the new flag
was for the kernel to use internally, and we sort of forgot that we were
also adding a user-visible flag.

>> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
>
> Thanks for doing this!
> Acked-by: Michal Hocko <mhocko@...e.com>

Thanks.

cheers