x86-64, NUMA: Better explain numa_distance handling
Handling of out-of-bounds distances and allocation failure can use better documentation. Add it. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Yinghai Lu <yinghai@kernel.org> Acked-by: David Rientjes <rientjes@google.com>
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					 2 changed files with 15 additions and 2 deletions
				
			
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			@ -392,11 +392,12 @@ void __init numa_reset_distance(void)
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{
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	size_t size = numa_distance_cnt * numa_distance_cnt * sizeof(numa_distance[0]);
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	/* numa_distance could be 1LU marking allocation failure, test cnt */
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	if (numa_distance_cnt)
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		memblock_x86_free_range(__pa(numa_distance),
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					__pa(numa_distance) + size);
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	numa_distance_cnt = 0;
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	numa_distance = NULL;
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	numa_distance = NULL;	/* enable table creation */
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}
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static int __init numa_alloc_distance(void)
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			@ -447,6 +448,14 @@ static int __init numa_alloc_distance(void)
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 * Set the distance from node @from to @to to @distance.  If distance table
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 * doesn't exist, one which is large enough to accomodate all the currently
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 * known nodes will be created.
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 *
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 * If such table cannot be allocated, a warning is printed and further
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 * calls are ignored until the distance table is reset with
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 * numa_reset_distance().
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 *
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 * If @from or @to is higher than the highest known node at the time of
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 * table creation or @distance doesn't make sense, the call is ignored.
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 * This is to allow simplification of specific NUMA config implementations.
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 */
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void __init numa_set_distance(int from, int to, int distance)
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{
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			@ -379,7 +379,11 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
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		if (emu_nid_to_phys[i] == NUMA_NO_NODE)
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			emu_nid_to_phys[i] = 0;
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	/* transform distance table */
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	/*
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	 * Transform distance table.  numa_set_distance() ignores all
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	 * out-of-bound distances.  Just call it for every possible node
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	 * combination.
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	 */
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	numa_reset_distance();
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	for (i = 0; i < MAX_NUMNODES; i++) {
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		for (j = 0; j < MAX_NUMNODES; j++) {
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