linux-kernel - Re: [PATCH] mm/mincore: allow for making sys

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Message-ID: <nycvar.YFH.7.76.1901100852080.6626@cbobk.fhfr.pm>
Date:   Thu, 10 Jan 2019 08:54:23 +0100 (CET)
From:   Jiri Kosina <jikos@...nel.org>
To:     Dave Chinner <david@...morbit.com>
cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jann Horn <jannh@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>, Linux-MM <linux-mm@...ck.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged

On Thu, 10 Jan 2019, Dave Chinner wrote:

> > Yeah, preadv2(RWF_NOWAIT) is in the same teritory as mincore(), it has 
> > "just" been overlooked. I can't speak for Daniel, but I believe he might 
> > be ok with rephrasing the above as "Restricting mincore() and RWF_NOWAIT 
> > is sufficient ...".
> 
> Good luck with restricting RWF_NOWAIT. I eagerly await all the
> fstests that exercise both the existing and new behaviours to
> demonstrate they work correctly.

Well, we can still resurrect my original aproach of doing this opt-in 
based on a sysctl setting, and letting the admin choose his poison.

If 'secure' mode is selected, RWF_NOWAIT will then probably just always 
fail wit EAGAIN.

-- 
Jiri Kosina
SUSE Labs