From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: MailingLists <haishan.bai@gmail.com>
Cc: tony.luck@intel.com, Peter Zijlstra <a.p.zijlstra@chello.nl>,
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 19:07:15 +1000 [thread overview]
Message-ID: <1310720835.4968.311.camel@pasglop> (raw)
In-Reply-To: <4E1FFC7B.4000209@gmail.com>
On Fri, 2011-07-15 at 16:38 +0800, MailingLists wrote:
> A page could be set to read only by the kernel (supervisor in the
> powerpc
> literature) on the e500, and that's what the kernel do. Set
> SW(supervisor
> write) bit in the TLB entry to grant write permission to the kernel on
> a
> page.
>
> And further the SW bit is set according to the DIRTY flag of the PTE,
> PTE.DIRTY is set in the do_page_fault(), the futex_lock_pi() disabled
> page fault, the PTE.DIRTY never can be set, so do the SW bit,
> unbreakable
> COW occurred, infinite loop followed.
That would be it ... the SW dirty and young tracking relies on faults to
fixup things in handle_pte_fault(). If the "disable page fault" thingy
happens before we get there, then we have a pretty nasty bug. Note that
this will hit more than just e500 (and in fact any architecture that
relies on SW to do dirty and young tracking).
Cheers,
Ben.
next prev parent reply other threads:[~2011-07-15 9:07 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
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 [this message]
2011-07-15 9:05 ` Benjamin Herrenschmidt
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