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Date:   Wed, 16 Jan 2019 12:18:11 +0000
From:   Kevin Easton <kevin@guarana.org>
To:     Josh Snyder <joshs@netflix.com>
Cc:     Dominique Martinet <asmadeus@codewreck.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Dave Chinner <david@fromorbit.com>,
        Jiri Kosina <jikos@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Jann Horn <jannh@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Michal Hocko <mhocko@suse.com>, Linux-MM <linux-mm@kvack.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged
Message-ID: <20190116121811.GA6971@ip-172-31-15-78>
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On Tue, Jan 15, 2019 at 11:52:25PM -0800, Josh Snyder wrote:
> On Tue, Jan 15, 2019 at 10:34 PM Dominique Martinet <asmadeus@codewreck.org>
> wrote:
> >
> > There is a difference with your previous patch though, that used to list no
> > page in core when it didn't know; this patch lists pages as in core when it
> > refuses to tell. I don't think that's very important, though.
> 
> Is there a reason not to return -EPERM in this case?

When I was looking through the Debian Code Search results, quite a few
of the hits were for code that uses mincore() as a way to check if
_anything_ is mapped at an address or not.  This code doesn't care about
the in core / not in core result of mincore(), just whether it returned
an error or not.

I think a new error return would break most of the instances of that
code I saw.

    - Kevin