Bug in reclaim logic with exhausted nodes?

[Christoph Lameter]

On Thu, 27 Mar 2014, Nishanth Aravamudan wrote:

> > That looks to be the correct way to handle things. Maybe mark the node as
> > offline or somehow not present so that the kernel ignores it.
>
> This is a SLUB condition:
>
> mm/slub.c::early_kmem_cache_node_alloc():
> ...
>         page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
> ...

So the page allocation from the node failed. We have a strange boot
condition where the OS is aware of anode but allocations on that node
fail.

 >         if (page_to_nid(page) != node) {
>                 printk(KERN_ERR "SLUB: Unable to allocate memory from "
>                                 "node %d\n", node);
>                 printk(KERN_ERR "SLUB: Allocating a useless per node structure "
>                                 "in order to be able to continue\n");
>         }
> ...
>
> Since this is quite early, and we have not set up the nodemasks yet,
> does it make sense to perhaps have a temporary init-time nodemask that
> we set bits in here, and "fix-up" those nodes when we setup the
> nodemasks?

Please take care of this earlier than this. The page allocator in general
should allow allocations from all nodes with memory during boot,