Re: [PATCH 5/5] mm: clear N_HIGH_MEMORY map before se set it again-v2

From: Andrew Morton
Date: Thu May 14 2009 - 12:57:05 EST


On Thu, 14 May 2009 09:43:22 -0700
Yinghai Lu <yinghai@xxxxxxxxxx> wrote:

>
> incase some system strange SRAT table. some kind of small range.
> or with mem= etc
>

That description is very hard to understand. Please provide more details.

>
> Signed-off-by: Yinghai Lu <Yinghai@xxxxxxxxxx>
> Tested-by: Jack Steiner <steiner@xxxxxxx>

What reason did Jack have to test this? Perhaps he hit some bug?
If so, please fully describe that bug in the changelog.


> Index: linux-2.6/mm/page_alloc.c
> ===================================================================
> --- linux-2.6.orig/mm/page_alloc.c
> +++ linux-2.6/mm/page_alloc.c
> @@ -4041,6 +4047,11 @@ void __init free_area_init_nodes(unsigne
> early_node_map[i].start_pfn,
> early_node_map[i].end_pfn);
>
> + /*
> + * find_zone_movable_pfns_for_nodes/early_calculate_totalpages init
> + * that node_mask, clear it at first
> + */
> + nodes_clear(node_states[N_HIGH_MEMORY]);
> /* Initialise every node */
> mminit_verify_pageflags_layout();
> setup_nr_node_ids();

If CONFIG_HIGHMEM=n, this will clear the N_NORMAL_MEMORY entry in
node_states[]. Why is this correct and desirable?

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