From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jiri Kosina <jikos@kernel.org>, Masatake YAMATO <yamato@redhat.com>
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 13:54:03 -0800 [thread overview]
Message-ID: <CAHk-=wgrSKyN23yp-npq6+J-4pGqbzxb3mJ183PryjHw7PWDyA@mail.gmail.com> (raw)
In-Reply-To: <nycvar.YFH.7.76.1901052131480.16954@cbobk.fhfr.pm>
On Sat, Jan 5, 2019 at 12:43 PM Jiri Kosina <jikos@kernel.org> wrote:
>
> > 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.
Yeah, heh.
And the first hit is 'fincore', which probably nobody cares about
anyway, but it does
fd = open (name, O_RDONLY)
..
mmap(window, len, PROT_NONE, MAP_PRIVATE, ..
so if we want to keep that working, we'd really need to actually check
file ownership rather than just looking at f_mode.
But I don't know if anybody *uses* and cares about fincore, and it's
particularly questionable for non-root users.
And the Android go runtime code seems to oddly use mincore to figure
out page size:
// try using mincore to detect the physical page size.
// mincore should return EINVAL when address is not a multiple of
system page size.
which is all kinds of odd, but whatever.. Why mincore, rather than
something sane and obvious like mmap? Don't ask me...
Anyway, the Debian code search just results in mostly non-present
stuff. It's sad that google code search is no more. It was great for
exactly these kinds of questions.
The mono runtime seems to have some mono_pages_not_faulted() function,
but I don't know if people use it for file mappings, and I couldn't
find any interesting users of it.
I didn't find anything that seems to really care, but I gave up after
a few pages of really boring stuff.
Linus
next prev parent reply other threads:[~2019-01-05 21:54 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
2019-01-05 21:54 ` Linus Torvalds [this message]
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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