Messages in this thread | | | Date | Thu, 15 Aug 2013 11:03:50 -0700 | From | Dave Hansen <> | Subject | Re: [PATCH 2/4] mm/sparse: introduce alloc_usemap_and_memmap |
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On 08/14/2013 05:31 PM, Wanpeng Li wrote: > After commit 9bdac91424075("sparsemem: Put mem map for one node together."), > vmemmap for one node will be allocated together, its logic is similiar as > memory allocation for pageblock flags. This patch introduce alloc_usemap_and_memmap > to extract the same logic of memory alloction for pageblock flags and vmemmap.
Shame on whoever copy-n-pasted that in the first place.
> - > - for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) { > - struct mem_section *ms; > - > - if (!present_section_nr(pnum)) > - continue; > - ms = __nr_to_section(pnum); > - nodeid_begin = sparse_early_nid(ms); > - pnum_begin = pnum; > - break; > - } > - usemap_count = 1; > - for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) { > - struct mem_section *ms; > - int nodeid; > - > - if (!present_section_nr(pnum)) > - continue; > - ms = __nr_to_section(pnum); > - nodeid = sparse_early_nid(ms); > - if (nodeid == nodeid_begin) { > - usemap_count++; > - continue; > - } > - /* ok, we need to take cake of from pnum_begin to pnum - 1*/ > - sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum, > - usemap_count, nodeid_begin); > - /* new start, update count etc*/ > - nodeid_begin = nodeid; > - pnum_begin = pnum; > - usemap_count = 1; > - } > - /* ok, last chunk */ > - sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS, > - usemap_count, nodeid_begin); > + alloc_usemap_and_memmap(usemap_map, true); ... > + alloc_usemap_and_memmap((unsigned long **)map_map, false); > #endif
Why does alloc_usemap_and_memmap() take an 'unsigned long **'? 'unsigned long' is for the usemap and 'struct page' is for the memmap. It's misleading to have it take an 'unsigned long **' and then just cast it over to a 'struct page **' internally.
Also, what's the point of having a function that returns something in a double-pointer, but that doesn't use its return value?
alloc_usemap_and_memmap() also needs a comment about what it's doing with that pointer and its other argument.
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