From: Hugh Dickins <hugh@veritas.com>
To: Andi Kleen <ak@suse.de>
Cc: Zoltan Menyhart <Zoltan.Menyhart@bull.net>,
Christoph Lameter <clameter@sgi.com>,
linux-mm@kvack.org, Zoltan.Menyhart@free.fr
Subject: Re: RFC: RCU protected page table walking
Date: Wed, 3 May 2006 19:00:25 +0100 (BST) [thread overview]
Message-ID: <Pine.LNX.4.64.0605031847190.15463@blonde.wat.veritas.com> (raw)
In-Reply-To: <200605031846.51657.ak@suse.de>
On Wed, 3 May 2006, Andi Kleen wrote:
>
> The page is not freed until all CPUs who had the mm mapped are flushed.
> See mmu_gather in asm-generic/tlb.h
>
> > Even if this security window is small, it does exist.
>
> It doesn't at least on architectures that use the generic tlbflush.h
Those architectures (including i386 and x86_64) which #define their
__pte_free_tlb etc. to tlb_remove_page are safe as is. But Zoltan's
ia64 #defines it to pte_free, which looks like it may free_page before
the TLB flush. But it is surprising if it has actually been unsafe
there on ia64 - perhaps Christoph can explain how it is safe?
Hugh
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next prev parent reply other threads:[~2006-05-03 18:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-03 15:31 Zoltan Menyhart
2006-05-03 16:46 ` Andi Kleen
2006-05-03 18:00 ` Hugh Dickins [this message]
2006-05-03 23:54 ` Christoph Lameter
2006-05-04 2:51 ` Chen, Kenneth W
2006-05-04 4:28 ` Hugh Dickins
2006-05-04 9:26 ` Zoltan Menyhart
2006-05-04 9:31 ` Andi Kleen
2006-05-04 11:32 ` Zoltan Menyhart
2006-05-04 12:00 ` Andi Kleen
2006-05-04 13:13 ` Robin Holt
2006-05-04 13:54 ` Zoltan Menyhart
2006-05-04 15:27 ` Hugh Dickins
2006-05-04 9:19 ` Zoltan Menyhart
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