From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: David Laight <David.Laight@ACULAB.COM>
Cc: tony.luck@intel.com, Shan Hai <haishan.bai@gmail.com>,
linux-kernel@vger.kernel.org, cmetcalf@tilera.com,
dhowells@redhat.com, paulus@samba.org, tglx@linutronix.de,
walken@google.com, linuxppc-dev@lists.ozlabs.org,
akpm@linux-foundation.org
Subject: RE: [PATCH 0/1] Fixup write permission of TLB on powerpc e500 core
Date: Fri, 15 Jul 2011 12:39:30 +0200 [thread overview]
Message-ID: <1310726370.2586.312.camel@twins> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6D8ADFC@saturn3.aculab.com>
On Fri, 2011-07-15 at 11:32 +0100, David Laight wrote:
> > The fault causing futex_atomic_cmpxchg_inatomic() is
> > protected by pagefault_disable(), so the page fault handler has
> > no chance to toggle the SW dirty/young tracking.
>=20
> Perhaps that is the bug!
> Whatever pagefault_disable() does, it shouldn't disable the
> SW dirty/young tracking - which should only needs bits moving
> in the page table itself (and TLB update??) rather than any
> operations on the rest of the data areas.
>=20
> It looks to me as though this could happen any time a page
> is marked inaccessible by the dirty/young tracking.
> Not just as a result of COW.
I've thought of that as well, but couldn't find the actual code in the
ppc fault bits. It could be it relies on vma information to know what it
should allow due to lack of bits in the pte.
If it requires the vma, it requires mmap_sem and it thus has to avoid
the whole thing when pagefault_disabled().
next prev parent reply other threads:[~2011-07-15 18:24 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
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 [this message]
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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