Re: [patch 2/3] Fix GFP_THISNODE behavior for memoryless nodes

[Christoph Lameter <clameter@sgi.com>]

On Thu, 14 Jun 2007, Lee Schermerhorn wrote:

> > That check is already done by __alloc_pages.
> 
> You mean in get_page_from_freelist()?  No, it only checks that the zone
> under consideration is on the same node as the zone at the start of the
> list.  This can be off-node if the node is populated only at lower
> zones; and the zonelists are in zone-order.

See the later discussion. I did not see the use the nodes pgdat here that 
you only have in alloc_pages_node().

> > Ummm... Slub would need to consult node_memory_map instead I guess.
> 
> Probably should check the node_memory_map to avoid attempting
> allocations from completely memoryless nodes.  However, it should still
> be able to handle nulls from alloc_pages_nodes() because of the
> scenarios discussed above.

It is able to handle NULLs during usual operations but not during bootstrap.

> Again, node_memory_map can't detect the "first zone in zonelist
> off-node" situation.  That's the one that alloc_pages_node() must guard
> against.   So, it can/should/must return NULL when attempting to
> allocate from a higher zone that is off-node.

I think GFP_THISNODE should not fail in that case.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>