linux-kernel - Re: [PATCH v1 0/3] perf/binfmt/mm: remove in-tree usage of MAP

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Date:   Wed, 21 Apr 2021 22:56:06 +0200
From:   David Hildenbrand <david@...hat.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Mike Rapoport <rppt@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Kevin Brodsky <Kevin.Brodsky@....com>,
        Michal Hocko <mhocko@...e.com>,
        Feng Tang <feng.tang@...el.com>,
        Don Zickus <dzickus@...hat.com>, x86@...nel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v1 0/3] perf/binfmt/mm: remove in-tree usage of
 MAP_EXECUTABLE

On 21.04.21 21:03, Eric W. Biederman wrote:
> David Hildenbrand <david@...hat.com> writes:
> 
>> Stumbling over the history of MAP_EXECUTABLE, I noticed that we still
>> have some in-tree users that we can get rid of.
>>
>> A good fit for the whole series could be Andrew's tree.
> 
> In general this looks like a good cleanup.
> 
> Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> 
> As far as I can see we can go after MAP_DENYWRITE the same way.
> Today deny_write_access in open_exec is what causes -ETXTBSY
> when attempting to write to file that is current executing.
> 
> Do you have any plans to look at that?

I did have a look and thought about ripping out MAP_DENYWRITE; I'm still 
in the process of connecting the pieces.

Some VM_DENYWRITE e.g., in mm/khugepaged.c still gives me a headache , 
and I'll have to double-check whether it would be okay to just fallback 
on checking the actual vm->file.

-- 
Thanks,

David / dhildenb