From: Rusty Russell <rusty@rustcorp.com.au>
To: Zachary Amsden <zach@vmware.com>
Cc: Linus Torvalds <torvalds@osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Chris Wright <chrisw@sous-sol.org>,
stable@kernel.org,
Virtualization Mailing List <virtualization@lists.osdl.org>,
Andi Kleen <ak@suse.de>
Subject: Re: [PATCH] Fix preemptible lazy mode bug
Date: Thu, 06 Sep 2007 06:37:46 +1000 [thread overview]
Message-ID: <1189024666.10802.197.camel@localhost.localdomain> (raw)
In-Reply-To: <46CE70C8.2030005@vmware.com>
On Thu, 2007-08-23 at 22:46 -0700, Zachary Amsden wrote:
> I recently sent off a fix for lazy vmalloc faults which can happen under
> paravirt when lazy mode is enabled. Unfortunately, I jumped the gun a
> bit on fixing this. I neglected to notice that since the new call to
> flush the MMU update queue is called from the page fault handler, it can
> be pre-empted. Both VMI and Xen use per-cpu variables to track lazy
> mode state, as all previous calls to set, disable, or flush lazy mode
> happened from a non-preemptable state.
Hi Zach,
I don't think this patch does anything. The flush is because we want
the just-completed "set_pte" to have immediate effect, so if preempt is
enabled we're already screwed because we can be moved between set_pte
and the arch_flush_lazy_mmu_mode() call.
Now, where's the problem caller? By my reading or rc4, vmalloc faults
are fixed up before enabling interrupts.
Confused,
Rusty.
next prev parent reply other threads:[~2007-09-05 20:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <46CE70C8.2030005@vmware.com>
2007-08-24 6:53 ` [PATCH] Fix preemptible lazy mode bug Jeremy Fitzhardinge
2007-08-24 6:59 ` Zachary Amsden
2007-08-25 11:57 ` Rusty Russell
2007-09-01 21:09 ` Jeremy Fitzhardinge
2007-09-03 20:14 ` Rusty Russell
2007-09-04 13:42 ` Jeremy Fitzhardinge
2007-09-05 16:33 ` Rusty Russell
2007-09-05 17:05 ` Zachary Amsden
2007-09-05 17:48 ` Rusty Russell
2007-09-05 20:10 ` Jeremy Fitzhardinge
2007-09-05 20:37 ` Rusty Russell [this message]
2007-09-05 23:49 ` Zachary Amsden
2007-09-06 5:41 ` Andi Kleen
2007-09-06 9:56 ` Jeremy Fitzhardinge
2007-09-06 9:57 ` Jeremy Fitzhardinge
2007-08-24 5:46 Zachary Amsden
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