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SubjectRe: -mm merge plans for 2.6.26 (memcgroup)
> On Mon, 21 Apr 2008 09:30:59 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Mon, 21 Apr 2008 00:51:30 +0100 (BST)
> Hugh Dickins <hugh@veritas.com> wrote:
> > > disable-the-memory-controller-by-default-v3.patch
> > > disable-the-memory-controller-by-default-v3-fix.patch
> >
> > If those are to go in, then the sooner the better, yes.
> >
> > But though I argued for cgroup_disable=memory (or some such),
> > I think myself that taking it even further now (requiring an
> > additional cgroup_enable=memory at boottime to get the memcg
> > stuff you chose with CGROUP_MEM_RES_CTLR=y at build time) is
> > confusing overkill, just messing around.

Yes, it does sound a bit silly. I'd say just enable it, and provide a
cgroup_disable.

> > Others think differently. A compromise would be to improve the
> > helptext for CGROUP_MEM_RES_CTLR (some of it is presently nonsense,
> > isn't it? Certainly there's a significant overhead, but it's the
> > 32-bit struct page not the 64-bit which then suffers from crossing
> > cacheline boundaries). Not much point in mentioning
> > cgroup_disable=memory if those patches go in, but needs to say
> > cgroup_enable=memory bootoption also needed.
> >
> My concern around this is "default" action of cgroups may be different
> from each otther. It's confusing...
>
>
> > > memcgroup-check-and-initialize-page-cgroup-in-memmap_init_zone.patch
> >
> > No, it was a good find from Shi, but you were right to think the patch
> > fishy, and Kame put in lots of work (thank you!) to identify the actual
> > culprit: he and Mel are discussing what the actual fix should be; and
> > we might want to choose a different fix for stable than for 2.6.26.
> >
> > I think you should drop that memmap_init_zone patch: the cgroup
> > pointer is not the only field we assume is zeroed, both flags and
> > mapping can cause trouble if they were not originally zeroed.
> > Re-zero the whole struct page? No, far better to fix the
> > root of the corruption, that Kame and Mel are working on.
> >
> I'll test and repodt Mel's patch later. I think Shi's patch will be
> unnecessary.

OK, I'll drop that one.

Thanks - it helps.



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