From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>, Jan Kara <jack@suse.cz>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Tony Luck <tony.luck@intel.com>
Subject: Re: Dirty/Access bits vs. page content
Date: Wed, 23 Apr 2014 16:14:15 +1000 [thread overview]
Message-ID: <1398233655.19682.135.camel@pasglop> (raw)
In-Reply-To: <CA+55aFw7JjEBUJRHXuwc7bGBD5c=J41mt46ovwHKAoMfPowWOw@mail.gmail.com>
On Tue, 2014-04-22 at 21:23 -0700, Linus Torvalds wrote:
>
> But I'm starting to consider this whole thing to be a 3.16 issue by
> now. It wasn't as simple as it looked, and while our old location of
> set_page_dirty() is clearly wrong, and DaveH even got a test-case for
> it (which I initially doubted would even be possible), I still
> seriously doubt that anybody sane who cares about data consistency
> will do concurrent unmaps (or MADV_DONTNEED) while another writer is
> actively using that mapping.
I'm more worried about users of unmap_mapping_ranges() than concurrent
munmap(). Things like the DRM playing tricks like swapping a mapping
from memory to frame buffer and vice-versa.
In any case, I agree with delaying that for 3.16, it's still very
unlikely that we hit this in any case that actually matters.
Cheers,
Ben.
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WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>, Jan Kara <jack@suse.cz>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Tony Luck <tony.luck@intel.com>
Subject: Re: Dirty/Access bits vs. page content
Date: Wed, 23 Apr 2014 16:14:15 +1000 [thread overview]
Message-ID: <1398233655.19682.135.camel@pasglop> (raw)
Message-ID: <20140423061415.uicygKRHEuW7V3dN2Z011diF0UIGbY8eLn4heCR3oXw@z> (raw)
In-Reply-To: <CA+55aFw7JjEBUJRHXuwc7bGBD5c=J41mt46ovwHKAoMfPowWOw@mail.gmail.com>
On Tue, 2014-04-22 at 21:23 -0700, Linus Torvalds wrote:
>
> But I'm starting to consider this whole thing to be a 3.16 issue by
> now. It wasn't as simple as it looked, and while our old location of
> set_page_dirty() is clearly wrong, and DaveH even got a test-case for
> it (which I initially doubted would even be possible), I still
> seriously doubt that anybody sane who cares about data consistency
> will do concurrent unmaps (or MADV_DONTNEED) while another writer is
> actively using that mapping.
I'm more worried about users of unmap_mapping_ranges() than concurrent
munmap(). Things like the DRM playing tricks like swapping a mapping
from memory to frame buffer and vice-versa.
In any case, I agree with delaying that for 3.16, it's still very
unlikely that we hit this in any case that actually matters.
Cheers,
Ben.
next prev parent reply other threads:[~2014-04-23 6:14 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1398032742.19682.11.camel@pasglop>
[not found] ` <CA+55aFz1sK+PF96LYYZY7OB7PBpxZu-uNLWLvPiRz-tJsBqX3w@mail.gmail.com>
[not found] ` <1398054064.19682.32.camel@pasglop>
[not found] ` <1398057630.19682.38.camel@pasglop>
[not found] ` <CA+55aFwWHBtihC3w9E4+j4pz+6w7iTnYhTf4N3ie15BM9thxLQ@mail.gmail.com>
[not found] ` <53558507.9050703@zytor.com>
2014-04-21 22:29 ` Dirty/Access bits vs. page content Linus Torvalds
2014-04-21 22:44 ` Dave Hansen
2014-04-22 0:31 ` Linus Torvalds
2014-04-22 0:44 ` Linus Torvalds
2014-04-22 5:15 ` Tony Luck
2014-04-22 5:15 ` Tony Luck
2014-04-22 14:55 ` Linus Torvalds
2014-04-22 14:55 ` Linus Torvalds
2014-04-22 7:34 ` Peter Zijlstra
2014-04-22 7:34 ` Peter Zijlstra
2014-04-22 7:54 ` Peter Zijlstra
2014-04-22 7:54 ` Peter Zijlstra
2014-04-22 21:36 ` Linus Torvalds
2014-04-22 21:36 ` Linus Torvalds
2014-04-22 21:46 ` Dave Hansen
2014-04-22 21:46 ` Dave Hansen
2014-04-22 22:08 ` Linus Torvalds
2014-04-22 22:08 ` Linus Torvalds
2014-04-22 22:41 ` Dave Hansen
2014-04-22 22:41 ` Dave Hansen
2014-04-23 2:44 ` Linus Torvalds
2014-04-23 2:44 ` Linus Torvalds
2014-04-23 3:08 ` Hugh Dickins
2014-04-23 3:08 ` Hugh Dickins
2014-04-23 3:08 ` Hugh Dickins
2014-04-23 4:23 ` Linus Torvalds
2014-04-23 4:23 ` Linus Torvalds
2014-04-23 6:14 ` Benjamin Herrenschmidt [this message]
2014-04-23 6:14 ` Benjamin Herrenschmidt
2014-04-23 18:41 ` Jan Kara
2014-04-23 18:41 ` Jan Kara
2014-04-23 19:33 ` Linus Torvalds
2014-04-24 6:51 ` Peter Zijlstra
2014-04-24 6:51 ` Peter Zijlstra
2014-04-24 18:40 ` Hugh Dickins
2014-04-24 18:40 ` Hugh Dickins
2014-04-24 19:45 ` Linus Torvalds
2014-04-24 19:45 ` Linus Torvalds
2014-04-24 20:02 ` Hugh Dickins
2014-04-24 20:02 ` Hugh Dickins
2014-04-24 23:46 ` Linus Torvalds
2014-04-25 1:37 ` Benjamin Herrenschmidt
2014-04-25 1:37 ` Benjamin Herrenschmidt
2014-04-25 2:41 ` Benjamin Herrenschmidt
2014-04-25 2:46 ` Linus Torvalds
2014-04-25 2:46 ` Linus Torvalds
2014-04-25 2:50 ` H. Peter Anvin
2014-04-25 2:50 ` H. Peter Anvin
2014-04-25 2:50 ` H. Peter Anvin
2014-04-25 3:03 ` Linus Torvalds
2014-04-25 3:03 ` Linus Torvalds
2014-04-25 12:01 ` Hugh Dickins
2014-04-25 12:01 ` Hugh Dickins
2014-04-25 13:51 ` Peter Zijlstra
2014-04-25 13:51 ` Peter Zijlstra
2014-04-25 19:41 ` Hugh Dickins
2014-04-25 19:41 ` Hugh Dickins
2014-04-26 18:07 ` Peter Zijlstra
2014-04-26 18:07 ` Peter Zijlstra
2014-04-27 7:20 ` Peter Zijlstra
2014-04-27 7:20 ` Peter Zijlstra
2014-04-27 12:20 ` Hugh Dickins
2014-04-27 12:20 ` Hugh Dickins
2014-04-27 19:33 ` Peter Zijlstra
2014-04-27 19:33 ` Peter Zijlstra
2014-04-27 19:47 ` Linus Torvalds
2014-04-27 19:47 ` Linus Torvalds
2014-04-27 20:09 ` Hugh Dickins
2014-04-27 20:09 ` Hugh Dickins
2014-04-28 9:25 ` Peter Zijlstra
2014-04-28 9:25 ` Peter Zijlstra
2014-04-28 10:14 ` Peter Zijlstra
2014-04-28 10:14 ` Peter Zijlstra
2014-04-27 16:21 ` Linus Torvalds
2014-04-27 16:21 ` Linus Torvalds
2014-04-27 23:13 ` Benjamin Herrenschmidt
2014-04-25 16:54 ` Dave Hansen
2014-04-25 16:54 ` Dave Hansen
2014-04-25 16:54 ` Dave Hansen
2014-04-25 18:41 ` Hugh Dickins
2014-04-25 18:41 ` Hugh Dickins
2014-04-25 22:00 ` Dave Hansen
2014-04-25 22:00 ` Dave Hansen
2014-04-25 22:00 ` Dave Hansen
2014-04-26 3:11 ` Hugh Dickins
2014-04-26 3:11 ` Hugh Dickins
2014-04-26 3:48 ` Linus Torvalds
2014-04-26 3:48 ` Linus Torvalds
2014-04-25 17:56 ` Linus Torvalds
2014-04-25 17:56 ` Linus Torvalds
2014-04-25 19:13 ` Hugh Dickins
2014-04-25 19:13 ` Hugh Dickins
2014-04-25 16:30 ` Dave Hansen
2014-04-25 16:30 ` Dave Hansen
2014-04-25 16:30 ` Dave Hansen
2014-04-23 20:11 ` Hugh Dickins
2014-04-23 20:11 ` Hugh Dickins
2014-04-24 8:49 ` Jan Kara
2014-04-24 8:49 ` Jan Kara
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