From: Tim Deegan <tim@xen.org>
To: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Cc: xen-devel@lists.xensource.com, ian.campbell@citrix.com,
andres@gridcentric.ca, keir.xen@gmail.com, jbeulich@suse.com,
ian.jackson@citrix.com, adin@gridcentric.ca
Subject: Re: [PATCH 03 of 12] x86/mm: Add per-page locking for memory sharing, when audits are disabled
Date: Thu, 19 Jan 2012 13:13:14 +0000 [thread overview]
Message-ID: <20120119131314.GL66164@ocelot.phlegethon.org> (raw)
In-Reply-To: <300ebad65ef953dac0d27446195232d3.squirrel@webmail.lagarcavilla.org>
At 05:06 -0800 on 19 Jan (1326949574), Andres Lagar-Cavilla wrote:
> > At 21:56 -0500 on 15 Jan (1326664583), Andres Lagar-Cavilla wrote:
> >> @@ -510,26 +684,63 @@ int mem_sharing_share_pages(struct domai
> >> smfn = get_gfn(sd, sgfn, &smfn_type);
> >> cmfn = get_gfn(cd, cgfn, &cmfn_type);
> >>
> >> - ret = XEN_DOMCTL_MEM_SHARING_S_HANDLE_INVALID;
> >> - spage = mem_sharing_lookup(mfn_x(smfn));
> >> - if ( spage == NULL )
> >> + /* This tricky business is to avoid two callers deadlocking if
> >> + * grabbing pages in opposite client/source order */
> >
> > I think you need to delete the XXX comment just above. :)
> >
> Well, that XXX comment applies if get_gfn locks the p2m, and then what
> we're grabbing in mem_sharing_lookup are lock per mfn, essentially. To
Oh, I see - wrong deadlock!. :)
Tim.
next prev parent reply other threads:[~2012-01-19 13:13 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 2:56 [PATCH 00 of 12] Sharing overhaul Andres Lagar-Cavilla
2012-01-16 2:56 ` [PATCH 01 of 12] x86/mm: Eliminate hash table in sharing code as index of shared mfns Andres Lagar-Cavilla
2012-01-19 11:39 ` Tim Deegan
2012-01-19 13:12 ` Andres Lagar-Cavilla
2012-01-16 2:56 ` [PATCH 02 of 12] x86/mm: Update mem sharing interface to (re)allow sharing of grants Andres Lagar-Cavilla
2012-01-19 11:56 ` Tim Deegan
2012-01-16 2:56 ` [PATCH 03 of 12] x86/mm: Add per-page locking for memory sharing, when audits are disabled Andres Lagar-Cavilla
2012-01-19 12:13 ` Tim Deegan
2012-01-19 13:02 ` Tim Deegan
2012-01-19 13:06 ` Andres Lagar-Cavilla
2012-01-19 13:13 ` Tim Deegan [this message]
2012-01-16 2:56 ` [PATCH 04 of 12] x86/mm: Enforce lock ordering for sharing page locks Andres Lagar-Cavilla
2012-01-19 12:18 ` Tim Deegan
2012-01-16 2:56 ` [PATCH 05 of 12] x86/mm: Check how many mfns are shared, in addition to how many are saved Andres Lagar-Cavilla
2012-01-16 2:56 ` [PATCH 06 of 12] x86/mm: New domctl: add a shared page to the physmap Andres Lagar-Cavilla
2012-01-19 13:04 ` Tim Deegan
2012-01-19 13:09 ` Andres Lagar-Cavilla
2012-01-16 2:56 ` [PATCH 07 of 12] Add the ability to poll stats about shared memory via the console Andres Lagar-Cavilla
2012-01-19 12:53 ` Tim Deegan
2012-01-16 2:56 ` [PATCH 08 of 12] x86/mm: use RCU in mem sharing audit list, eliminate global lock completely Andres Lagar-Cavilla
2012-01-19 12:59 ` Tim Deegan
2012-01-19 13:03 ` Andres Lagar-Cavilla
2012-01-19 13:14 ` Tim Deegan
2012-01-16 2:56 ` [PATCH 09 of 12] Update memshr API and tools Andres Lagar-Cavilla
2012-01-23 15:14 ` Ian Campbell
2012-01-16 2:56 ` [PATCH 10 of 12] Tools: Expose to libxc the total number of shared frames and space saved Andres Lagar-Cavilla
2012-01-16 2:56 ` [PATCH 11 of 12] Tools: Add a sharing command to xl for information about shared pages Andres Lagar-Cavilla
2012-01-19 12:14 ` Ian Campbell
2012-01-16 2:56 ` [PATCH 12 of 12] Memshrtool: tool to test and exercise the sharing subsystem Andres Lagar-Cavilla
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