linux-kernel - Re: Could we do immediate pte zaps in vunmap?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 27 Nov 2010 21:36:56 +1100
From:	Nick Piggin <npiggin@...nel.dk>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Nick Piggin <npiggin@...nel.dk>,
	"Xen-devel@...ts.xensource.com" <Xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Could we do immediate pte zaps in vunmap?

On Fri, Nov 26, 2010 at 12:10:51AM -0800, Jeremy Fitzhardinge wrote:
> What if vm_unmap_ram() and co. immediately zeroed out the ptes, but
> lazily deferred the tlb flushes?  It seems to me there's no benefit in
> batching up the pte clearing since that can't be amortized like the tlb
> flush.

Yes that can be done.


> I think that would solve the problem we have with the interactions
> between lazy unmap and Xen.  The issue is having stray pte entries
> around (because Xen keeps track of those as part of its page-type
> mechanism), but stale tlb entries are no problem.

It would be great if that solves it.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/