Re: [PATCH] vmemmap, memory_hotplug: fallback to base pages for vmmap

From: Michal Hocko
Date: Wed Jul 12 2017 - 05:04:14 EST


On Tue 11-07-17 17:45:41, Johannes Weiner wrote:
[...]
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index a56c3989f773..efd3f48c667c 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -52,18 +52,24 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
> {
> /* If the main allocator is up use that, fallback to bootmem. */
> if (slab_is_available()) {
> + unsigned int order;
> + static int warned;
> struct page *page;
> + gfp_t gfp_mask;
>
> + order = get_order(size);
> + gfp_mask = GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|__GFP_NOWARN;

why not do
gfp_mask = GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT;
if (warned)
gfp_mask |= __GFP_NOWARN;

and get the actual allocation warning from the allocation context. Then
we can keep the warning vmemmap_populate_hugepages because that would be
more descriptive that what is going on.

Btw. __GFP_REPEAT has been replaced by __GFP_RETRY_MAYFAIL in mmotm
tree.

> if (node_state(node, N_HIGH_MEMORY))
> - page = alloc_pages_node(
> - node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
> - get_order(size));
> + page = alloc_pages_node(node, gfp_mask, size);
> else
> - page = alloc_pages(
> - GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
> - get_order(size));
> + page = alloc_pages(gfp_mask, size);
> if (page)
> return page_address(page);
> + if (!warned) {
> + warn_alloc(gfp_mask, NULL,
> + "vmemmap alloc failure: order:%u", order);
> + warned = 1;
> + }
> return NULL;
> } else
> return __earlyonly_bootmem_alloc(node, size, size,

--
Michal Hocko
SUSE Labs