From: Jiri Kosina <jikos@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Greg KH <gregkh@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
linux-api@vger.kernel.org
Subject: Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged
Date: Sat, 5 Jan 2019 21:43:02 +0100 (CET) [thread overview]
Message-ID: <nycvar.YFH.7.76.1901052131480.16954@cbobk.fhfr.pm> (raw)
In-Reply-To: <CAHk-=whGmE4QVr6NbgHnrVGVENfM3s1y6GNbsfh8PcOg=6bpqw@mail.gmail.com>
On Sat, 5 Jan 2019, Linus Torvalds wrote:
> > I am still not completely sure what to return in such cases though; we can
> > either blatantly lie and always pretend that the pages are resident
>
> That's what my untested patch did. Or maybe just claim they are all
> not present?
Thinking about it a little bit more, I believe Vlastimil has a good point
with 'non present' potentially causing more bogus activity in userspace in
response (in an effort to actually make them present, and failing
indefinitely).
IOW, I think it's a reasonable expectation that the common scenario is
"check if it's present, and if not, try to fault it in" instead of "check
if it's present, and if it is, try to evict it".
> And again, that patch was entirely untested, so it may be garbage and
> have some fundamental problem.
I will be travelling for next ~24 hours, but I have just asked our QA guys
to run it through some basic battery of testing (which will probably
happen on monday anyway).
> I also don't know exactly what rule might make most sense, but "you can
> write to the file" certainly to me implies that you also could know what
> parts of it are in-core.
I think it's reasonable; I can't really imagine any sidechannel to a
global state be possibly mounted on valid R/W mappings. I'd guess that
probably the most interesting here are the code segments of shared
libraries, allowing to trace victim's execution.
> Who actually _uses_ mincore()? That's probably the best guide to what
> we should do. Maybe they open the file read-only even if they are the
> owner, and we really should look at file ownership instead.
Yeah, well
https://codesearch.debian.net/search?q=mincore
is a bit too much mess to get some idea quickly I am afraid.
--
Jiri Kosina
SUSE Labs
next prev parent reply other threads:[~2019-01-05 20:43 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-05 17:27 [PATCH] mm/mincore: allow for making sys_mincore() privileged Jiri Kosina
2019-01-05 19:14 ` Vlastimil Babka
2019-01-05 19:24 ` Jiri Kosina
2019-01-05 19:38 ` Vlastimil Babka
2019-01-08 9:14 ` Bernd Petrovitsch
2019-01-08 11:37 ` Jiri Kosina
2019-01-08 13:53 ` Bernd Petrovitsch
2019-01-08 14:08 ` Kirill A. Shutemov
2019-01-05 19:44 ` kbuild test robot
2019-01-05 19:46 ` Linus Torvalds
2019-01-05 20:12 ` Jiri Kosina
2019-01-05 20:17 ` Linus Torvalds
2019-01-05 20:43 ` Jiri Kosina [this message]
2019-01-05 21:54 ` Linus Torvalds
2019-01-06 11:33 ` Kevin Easton
2019-01-08 8:50 ` Kevin Easton
2019-01-18 14:23 ` Tejun Heo
2019-01-05 20:13 ` Linus Torvalds
2019-01-05 19:56 ` kbuild test robot
2019-01-05 22:54 ` Jann Horn
2019-01-05 23:05 ` Linus Torvalds
2019-01-05 23:16 ` Linus Torvalds
2019-01-05 23:28 ` Linus Torvalds
2019-01-05 23:39 ` Linus Torvalds
2019-01-06 0:11 ` Matthew Wilcox
2019-01-06 0:22 ` Linus Torvalds
2019-01-06 1:50 ` Linus Torvalds
2019-01-06 21:46 ` Linus Torvalds
2019-01-08 4:43 ` Dave Chinner
2019-01-08 17:57 ` Linus Torvalds
2019-01-09 2:24 ` Dave Chinner
2019-01-09 2:31 ` Jiri Kosina
2019-01-09 4:39 ` Dave Chinner
2019-01-09 10:08 ` Jiri Kosina
2019-01-10 1:15 ` Dave Chinner
2019-01-10 7:54 ` Jiri Kosina
2019-01-09 18:25 ` Linus Torvalds
2019-01-10 0:44 ` Dave Chinner
2019-01-10 1:18 ` Linus Torvalds
2019-01-10 5:26 ` Andy Lutomirski
2019-01-10 14:47 ` Matthew Wilcox
2019-01-10 21:44 ` Dave Chinner
2019-01-10 21:59 ` Linus Torvalds
2019-01-11 1:47 ` Dave Chinner
2019-01-10 7:03 ` Dave Chinner
2019-01-10 11:47 ` Linus Torvalds
2019-01-10 12:24 ` Dominique Martinet
2019-01-10 22:11 ` Linus Torvalds
2019-01-11 2:03 ` Dave Chinner
2019-01-11 2:18 ` Linus Torvalds
2019-01-11 4:04 ` Dave Chinner
2019-01-11 4:08 ` Andy Lutomirski
2019-01-11 7:20 ` Dave Chinner
2019-01-11 7:08 ` Linus Torvalds
2019-01-11 7:36 ` Dave Chinner
2019-01-11 16:26 ` Linus Torvalds
2019-01-15 23:45 ` Dave Chinner
2019-01-16 4:54 ` Linus Torvalds
2019-01-16 5:49 ` Linus Torvalds
2019-01-17 1:26 ` Dave Chinner
2019-02-20 15:49 ` Nicolai Stange
2019-01-11 4:57 ` Dominique Martinet
2019-01-11 7:11 ` Linus Torvalds
2019-01-11 7:32 ` Dominique Martinet
2019-01-16 0:42 ` Josh Snyder
2019-01-16 5:00 ` Linus Torvalds
2019-01-16 5:25 ` Andy Lutomirski
2019-01-16 5:34 ` Linus Torvalds
2019-01-16 5:46 ` Dominique Martinet
2019-01-16 5:58 ` Linus Torvalds
2019-01-16 6:34 ` Dominique Martinet
2019-01-16 7:52 ` Josh Snyder
2019-01-16 12:18 ` Kevin Easton
2019-01-17 21:45 ` Vlastimil Babka
2019-01-18 4:49 ` Linus Torvalds
2019-01-18 18:58 ` Vlastimil Babka
2019-01-16 16:12 ` Jiri Kosina
2019-01-16 17:48 ` Linus Torvalds
2019-01-16 20:23 ` Jiri Kosina
2019-01-16 21:37 ` Matthew Wilcox
2019-01-16 21:41 ` Jiri Kosina
2019-01-17 9:52 ` Cyril Hrubis
2019-01-28 13:49 ` Cyril Hrubis
2019-01-17 4:51 ` Linus Torvalds
2019-01-18 4:54 ` Linus Torvalds
2019-01-17 1:49 ` Dominique Martinet
2019-01-23 20:27 ` Linus Torvalds
2019-01-23 20:35 ` Linus Torvalds
2019-01-23 23:12 ` Jiri Kosina
2019-01-24 0:20 ` Linus Torvalds
2019-01-24 0:24 ` Dominique Martinet
2019-01-24 12:45 ` Dominique Martinet
2019-01-24 14:25 ` Jiri Kosina
2019-01-27 22:35 ` Jiri Kosina
2019-01-28 0:05 ` Dominique Martinet
2019-01-29 23:52 ` Jiri Kosina
2019-01-30 9:09 ` Michal Hocko
2019-01-30 12:29 ` Jiri Kosina
2019-01-16 12:36 ` Matthew Wilcox
2019-01-10 14:50 ` Matthew Wilcox
2019-01-11 7:36 ` Jiri Kosina
2019-01-17 2:22 ` Dave Chinner
2019-01-17 8:18 ` Jiri Kosina
2019-01-17 21:06 ` Dave Chinner
2019-01-07 4:32 ` Dominique Martinet
2019-01-07 10:33 ` Vlastimil Babka
2019-01-07 11:08 ` Dominique Martinet
2019-01-07 11:59 ` Vlastimil Babka
2019-01-07 13:29 ` Daniel Gruss
2019-01-07 10:10 ` Michael Ellerman
2019-01-05 23:09 ` Jiri Kosina
2019-01-30 12:44 ` [PATCH 0/3] mincore() and IOCB_NOWAIT adjustments Vlastimil Babka
2019-01-30 12:44 ` [PATCH 1/3] mm/mincore: make mincore() more conservative Vlastimil Babka
2019-01-31 9:43 ` Michal Hocko
2019-01-31 9:51 ` Dominique Martinet
2019-01-31 17:46 ` Josh Snyder
2019-02-01 8:56 ` Vlastimil Babka
2019-03-06 23:13 ` Andrew Morton
2019-03-07 0:01 ` Jiri Kosina
2019-03-07 0:40 ` Dominique Martinet
2019-03-07 5:46 ` Jiri Kosina
2019-01-30 12:44 ` [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O Vlastimil Babka
2019-01-30 15:04 ` Florian Weimer
2019-01-30 15:15 ` Jiri Kosina
2019-01-31 10:47 ` Florian Weimer
2019-01-31 11:34 ` Jiri Kosina
2019-01-31 9:56 ` Michal Hocko
2019-01-31 10:15 ` Jiri Kosina
2019-01-31 10:23 ` Michal Hocko
2019-01-31 10:30 ` Jiri Kosina
2019-01-31 11:32 ` Michal Hocko
2019-01-31 17:54 ` Linus Torvalds
2019-02-01 5:13 ` Dave Chinner
2019-02-01 7:05 ` Linus Torvalds
2019-02-01 7:21 ` Linus Torvalds
2019-02-01 1:44 ` Dave Chinner
2019-02-12 15:48 ` Jiri Kosina
2019-01-31 12:04 ` Daniel Gruss
2019-01-31 12:06 ` Vlastimil Babka
2019-01-31 12:08 ` Jiri Kosina
2019-01-31 12:57 ` Daniel Gruss
2019-01-30 12:44 ` [PATCH 3/3] mm/mincore: provide mapped status when cached status is not allowed Vlastimil Babka
2019-01-31 10:09 ` Michal Hocko
2019-02-01 9:04 ` Vlastimil Babka
2019-02-01 9:11 ` Michal Hocko
2019-02-01 9:27 ` Vlastimil Babka
2019-02-06 20:14 ` Jiri Kosina
2019-02-12 3:44 ` Jiri Kosina
2019-02-12 6:36 ` Michal Hocko
2019-02-12 13:09 ` Jiri Kosina
2019-02-12 14:01 ` Michal Hocko
2019-03-06 12:11 ` [PATCH 0/3] mincore() and IOCB_NOWAIT adjustments Jiri Kosina
2019-03-06 22:35 ` Andrew Morton
2019-03-06 22:48 ` Jiri Kosina
2019-03-06 23:23 ` Andrew Morton
2019-03-06 23:32 ` Dominique Martinet
2019-03-06 23:38 ` Andrew Morton
2019-03-09 16:53 ` Linus Torvalds
2019-03-12 14:17 ` [PATCH v2 0/2] prevent mincore() page cache leaks Vlastimil Babka
2019-03-12 14:17 ` [PATCH v2 1/2] mm/mincore: make mincore() more conservative Vlastimil Babka
2019-03-12 14:17 ` [PATCH v2 2/2] mm/mincore: provide mapped status when cached status is not allowed Vlastimil Babka
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