On 01/31/2014 02:05 AM, Petr Tesarik wrote:
> With DISCONTIGMEM, the mapping between a pfn and its owning node is
> initialized using data provided by the BIOS or from the command line.
> However, the initialization may fail if the extents are not aligned
> to section boundary (64M).
So is this a problem that shows up with DISCONTIGMEM? Just curious, but
what the heck kind of 32-bit NUMA hardware is still in the wild? Did
someon buy a NUMA-Q on eBay? :)
> void memory_present(int nid, unsigned long start, unsigned long end)
> {
> - unsigned long pfn;
> + unsigned long sect, endsect;
>
> printk(KERN_INFO "Node: %d, start_pfn: %lx, end_pfn: %lx\n",
> nid, start, end);
> printk(KERN_DEBUG " Setting physnode_map array to node %d for
> pfns:\n", nid);
> printk(KERN_DEBUG " ");
> - for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
> - physnode_map[pfn / PAGES_PER_SECTION] = nid;
> - printk(KERN_CONT "%lx ", pfn);
> + endsect = (end - 1) / PAGES_PER_SECTION;
> + for (sect = start / PAGES_PER_SECTION; sect <= endsect; ++sect) {
> + physnode_map[sect] = nid;
> + printk(KERN_CONT "%lx ", sect * PAGES_PER_SECTION);
> }
> printk(KERN_CONT "\n");
> }
So, if start and end are not aligned to section boundaries, we will miss
setting physnode_map[] for the final section?
For instance, if we have a 64MB section size and try to call
memory_present(32MB -> 96MB), we will set 0->64MB present, but not set
the 64MB->128MB section as present.
Right?
Can you just align 'start' down to the section's start and 'end' up to
the end of the section that contains it? I guess you do that
implicitly, but you should be able to do it without refactoring the for
loop entirely.
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