Re: 2.6.23-rc1-mm1: boot hang on ia64 with memoryless nodes

Lee Schermerhorn
2007-07-25T21:18:57Z

On Wed, 2007-07-25 at 12:38 -0700, Christoph Lameter wrote:
> (ccing Andy who did the work on the config stuff)
>
> On Wed, 25 Jul 2007, Lee Schermerhorn wrote:
>
> > I tried to deselect SPARSEMEM_VMEMMAP. Kconfig's "def_bool=y" wouldn't
> > let me :-(. After hacking the Kconfig and mm/sparse.c to allow that,
> > boot hangs with no error messages shortly after "Built N zonelists..."
> > message.
>
> I get a similar hang here and see the system looping in softirq / hrtimer
> code.
>
> > Backed off to DISCONTIGMEM+VIRTUAL_MEMORY_MAP, and saw same hang as with
> > (SPARSMEM && !SPARSEMEM_VMEMMAP).
>
> So its not related to SPARSE VMEMMAP? General VMEMMAP issue on IA64?

This hang is different from the one I see with SPARSE VMEMMAP -- no
"Unable to handle kernel paging request..." message. Just hangs after
"Built N zonelists..." and some message about "color" that I didn't
capture. Next time [:-(]...

>
> > I should mention that I have my test system in the "fully interleaved"
> > configuration for testing the memoryless node patches. This means that
> > nodes 0-3 [the real nodes with the cpus attached] have no memory. All
> > memory resides in a cpu-less pseudo-node. I'm wondering if
> > SPARSEMEM_VMEMMAP can handle this? 22-rc6-mm1 booted OK on this config
> > w/ SPARSEMEM_EXTREME.
>
> The vmemmap page table blocks get allocated on the nodes where there
> is actual mmemory but sparse.c may not have been updated to only look for
> memory on nodes that have memory. If it looks for online nodes then we
> may have an issue there. Andy?

In free_area_init_nodes(), free_area_init_node() [singular] is called
for_each_online_node... I'm looking into this. I might need an
additional memoryless node patch to test the memoryless node patches...

>
> Were you able to run discontig/vmemmap in the past with this
> configuration?

Yeah, way back ~2.6.14/15 or so. My configs have all used SPARSEMEM
since then.

I'm going to switch back to "100% cell local memory" and try again.
But, if you're seeing hangs w/o memoryless nodes, I'm not hopeful.

Later,
Lee