Re: [PATCH] sparsemem vmemmap: initialize memmap.

From: Heiko Carstens
Date: Fri May 09 2008 - 07:35:21 EST


> > Index: linux-2.6/mm/sparse-vmemmap.c
> > ===================================================================
> > --- linux-2.6.orig/mm/sparse-vmemmap.c
> > +++ linux-2.6/mm/sparse-vmemmap.c
> > @@ -154,6 +154,6 @@ struct page * __meminit sparse_mem_map_p
> > int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
> > if (error)
> > return NULL;
> > -
> > + memset(map, 0, PAGES_PER_SECTION * sizeof(struct page));
> > return map;
> > }
>
> The normal expectation is that all allocations are made using
> vmemmap_alloc_block() which allocates from the appropriate place. Once
> the buddy is up and available it uses:
>
> struct page *page = alloc_pages_node(node,
> GFP_KERNEL | __GFP_ZERO, get_order(size));
>
> to get the memory so it should all be zero'd. So I would expect all
> existing users to be covered by that? Can you not simply use __GFP_ZERO
> for your allocations or use vmemmap_alloc_block() ?

Ah, I didn't notice the __GFP_ZERO. So it's just an s390 bug. Will
move the memset to our code instead.
Thanks!
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