On (22/01/08 12:11), Christoph Lameter didst pronounce: > On Tue, 22 Jan 2008, Mel Gorman wrote: > > > Christoph/Pekka, this patch is papering over the problem and something > > more fundamental may be going wrong. The crash occurs because l3 is NULL > > and the cache is kmem_cache so this is early in the boot process. It is > > selecting l3 based on node 2 which is correct in terms of available memory > > but it initialises the lists on node 0 because that is the node the CPUs are > > located. Hence later it uses an uninitialised nodelists and BLAM. Relevant > > parts of the log for seeing the memoryless nodes in relation to CPUs is; > > Would it be possible to run the bootstrap on a cpu that has a > node with memory associated to it?
Not in the way the machine is currently configured. All the CPUs appear to be on a node with no memory. It's best to assume I cannot get the machine reconfigured (which just hides the bug anyway). Physically, it's thousands of miles away so I can't do the work. I can get lab support to do the job but that will take a fair while and at the end of the day, it doesn't tell us a lot. We know that other PPC64 machines work so it's not a general problem. > I believe we had the same situation > last year when GFP_THISNODE was introduced? > It feels vaguely familiar but I don't recall the details in sufficient detail to recognise if this is the same problem or not. > After you reverted the slab memoryless node patch there should be per node > structures created for node 0 unless the node is marked offline. Is it? If > so then you are booting a cpu that is associated with an offline node. > I'll roll a patch that prints out the online states before startup and see what it looks like. > > Can you see a better solution than this? > > Well this means that bootstrap will work by introducing foreign objects > into the per cpu queue (should only hold per cpu objects). They will > later be consumed and then the queues will contain the right objects so > the effect of the patch is minimal. > By minimal, do you mean that you expect it to break in some other respect later or minimal as in "this is bad but should not have no adverse impact". > I thought we fixed the similar situation last year by dropping > GFP_THISNODE for some allocations? > Whatever this was a problem fixed in the past or not, it's broken again now :( . It's possible that there is a __GFP_THISNODE that can be dropped early at boot-time that would also fix this problem in a way that doesn't affect runtime (like altering cache_grow in my patch does). -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
