From: Mike Frysinger <vapier.adi@gmail.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: tony.luck@intel.com, Peter Zijlstra <a.p.zijlstra@chello.nl>,
Shan Hai <haishan.bai@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, cmetcalf@tilera.com,
dhowells@redhat.com, paulus@samba.org,
uclinux-dist-devel@blackfin.uclinux.org, tglx@linutronix.de,
walken@google.com, linuxppc-dev@lists.ozlabs.org,
akpm@linux-foundation.org
Subject: Re: [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of dirty & young
Date: Tue, 26 Jul 2011 23:50:46 -0700 [thread overview]
Message-ID: <CAMjpGUdxpaYBFfKjBEPFOJohnKoXfagLUHvhrst+NembeabxcA@mail.gmail.com> (raw)
In-Reply-To: <1311049762.25044.392.camel@pasglop>
On Mon, Jul 18, 2011 at 21:29, Benjamin Herrenschmidt wrote:
> The futex code currently attempts to write to user memory within
> a pagefault disabled section, and if that fails, tries to fix it
> up using get_user_pages().
>
> This doesn't work on archs where the dirty and young bits are
> maintained by software, since they will gate access permission
> in the TLB, and will not be updated by gup().
>
> In addition, there's an expectation on some archs that a
> spurious write fault triggers a local TLB flush, and that is
> missing from the picture as well.
>
> I decided that adding those "features" to gup() would be too much
> for this already too complex function, and instead added a new
> simpler fixup_user_fault() which is essentially a wrapper around
> handle_mm_fault() which the futex code can call.
unfortunately, this breaks all nommu ports. you added
fixup_user_fault() to mm/memory.c only which is not used by nommu
logic.
-mike
next prev parent reply other threads:[~2011-07-27 6:51 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-15 8:07 [PATCH 0/1] Fixup write permission of TLB on powerpc e500 core Shan Hai
2011-07-15 8:07 ` [PATCH 1/1] " Shan Hai
2011-07-15 10:23 ` Peter Zijlstra
2011-07-15 15:18 ` Shan Hai
2011-07-15 15:24 ` Peter Zijlstra
2011-07-16 15:36 ` Shan Hai
2011-07-16 14:50 ` Shan Hai
2011-07-16 23:49 ` Benjamin Herrenschmidt
2011-07-17 9:38 ` Peter Zijlstra
2011-07-17 14:29 ` Benjamin Herrenschmidt
2011-07-17 23:14 ` Benjamin Herrenschmidt
2011-07-18 3:53 ` Benjamin Herrenschmidt
2011-07-18 4:02 ` Benjamin Herrenschmidt
2011-07-18 4:01 ` Benjamin Herrenschmidt
2011-07-18 6:48 ` Shan Hai
2011-07-18 7:01 ` Benjamin Herrenschmidt
2011-07-18 7:26 ` Shan Hai
2011-07-18 7:36 ` Benjamin Herrenschmidt
2011-07-18 7:50 ` Shan Hai
2011-07-19 3:30 ` Shan Hai
2011-07-19 4:20 ` Benjamin Herrenschmidt
2011-07-19 4:29 ` [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of dirty & young Benjamin Herrenschmidt
2011-07-19 4:55 ` Shan Hai
2011-07-19 5:17 ` Shan Hai
2011-07-19 5:24 ` Benjamin Herrenschmidt
2011-07-19 5:38 ` Shan Hai
2011-07-19 7:46 ` Benjamin Herrenschmidt
2011-07-19 8:24 ` Shan Hai
2011-07-19 8:26 ` [RFC/PATCH] mm/futex: Fix futex writes on archs with SW trackingof " David Laight
2011-07-19 8:45 ` Benjamin Herrenschmidt
2011-07-19 8:45 ` Shan Hai
2011-07-19 11:10 ` [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of " Peter Zijlstra
2011-07-20 14:39 ` Darren Hart
2011-07-21 22:36 ` Andrew Morton
2011-07-21 22:52 ` Benjamin Herrenschmidt
2011-07-21 22:57 ` Benjamin Herrenschmidt
2011-07-21 22:59 ` Andrew Morton
2011-07-22 1:40 ` Benjamin Herrenschmidt
2011-07-22 1:54 ` Shan Hai
2011-07-27 6:50 ` Mike Frysinger [this message]
2011-07-27 7:58 ` Benjamin Herrenschmidt
2011-07-27 8:59 ` Peter Zijlstra
2011-07-27 10:09 ` David Howells
2011-07-27 10:17 ` Peter Zijlstra
2011-07-27 10:20 ` Benjamin Herrenschmidt
2011-07-28 0:12 ` Mike Frysinger
2011-08-08 2:31 ` Mike Frysinger
2011-07-28 10:55 ` David Howells
2011-07-17 11:02 ` [PATCH 1/1] Fixup write permission of TLB on powerpc e500 core Peter Zijlstra
2011-07-17 13:33 ` Shan Hai
2011-07-17 14:48 ` Benjamin Herrenschmidt
2011-07-17 15:40 ` Shan Hai
2011-07-17 22:34 ` Benjamin Herrenschmidt
2011-07-17 14:34 ` Benjamin Herrenschmidt
2011-07-15 8:20 ` [PATCH 0/1] " Peter Zijlstra
2011-07-15 8:38 ` MailingLists
2011-07-15 8:44 ` Peter Zijlstra
2011-07-15 9:08 ` Shan Hai
2011-07-15 9:12 ` Benjamin Herrenschmidt
2011-07-15 9:50 ` Peter Zijlstra
2011-07-15 10:06 ` Shan Hai
2011-07-15 10:32 ` David Laight
2011-07-15 10:39 ` Peter Zijlstra
2011-07-15 15:32 ` Shan Hai
2011-07-16 0:20 ` Benjamin Herrenschmidt
2011-07-16 15:03 ` Shan Hai
2011-07-15 23:47 ` Benjamin Herrenschmidt
2011-07-15 9:07 ` Benjamin Herrenschmidt
2011-07-15 9:05 ` Benjamin Herrenschmidt
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