ARM: Whether a bank must be fully contained by a section?

[Wang Nan]

Hi Russell,

By reading the code of show_mem(), I found that there is an assumption
that the page structs must be continuous for each bank:

	for_each_bank (i, mi) {
		...
		page = pfn_to_page(pfn1);
		end  = pfn_to_page(pfn2 - 1) + 1;
	
		do {
			...
			page++;  <-- pageframe must be continuous
			...
		} while (page < end);
		...
	}

Therefore, a bank must be fully contained in a section in sparse memory
mode, because page frames are allocated section by section (in
sparse_init()).

However, I didn't find other code which enforces this assumption.
Instead, in arm_memory_present (arch/arm/mm/init.c), it seems that a
bank may contain more than one section:

arm_memory_present:
	...
	for_each_memblock(memory, reg)
		memory_present(0, memblock_region_memory_base_pfn(reg),
			       memblock_region_memory_end_pfn(reg));
	...

memory_present:
	...
	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
		...
	}
	...


Therefore, would you please consider the following patch, which removes
the assumption that a bank must be fully contained in one section?


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