Re: sparc64 bootup regression...

From: KAMEZAWA Hiroyuki
Date: Wed Apr 30 2008 - 02:42:20 EST


On Tue, 29 Apr 2008 23:38:32 -0700
Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Tue, 29 Apr 2008 23:12:41 -0700 (PDT) David Miller <davem@xxxxxxxxxxxxx> wrote:
>
> >
> > This commit causes bootup failures on sparc64:
> >
> > commit 86f6dae1377523689bd8468fed2f2dd180fc0560
> > Author: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
> > Date: Mon Apr 28 02:13:33 2008 -0700
> >
> > memory hotplug: allocate usemap on the section with pgdat
> >
> > Usemaps are allocated on the section which has pgdat by this.
> >
> > Because usemap size is very small, many other sections usemaps are allocated
> > on only one page. If a section has usemap, it can't be removed until removing
> > other sections. This dependency is not desirable for memory removing.
> >
> > Pgdat has similar feature. When a section has pgdat area, it must be the last
> > section for removing on the node. So, if section A has pgdat and section B
> > has usemap for section A, Both sections can't be removed due to dependency
> > each other.
> >
> > To solve this issue, this patch collects usemap on same section with pgdat.
> > If other sections doesn't have any dependency, this section will be able to be
> > removed finally.
>
> Thanks. Does a straightforward revert fix it? If so, we could do that while heads
> are being scratched.

I'm now digging. plz wait a bit.

Thanks,
-Kame

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