Messages in this thread | | | Subject | Re: [PATCH] ARM: mm: Regarding section when dealing with meminfo | From | Dave Hansen <> | Date | Thu, 20 Jan 2011 09:25:13 -0800 |
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On Thu, 2011-01-20 at 23:28 +0900, Minchan Kim wrote: > On Thu, Jan 20, 2011 at 06:45:39PM +0900, KyongHo Cho wrote: > > Sparsemem allows that a bank of memory spans over several adjacent > > sections if the start address and the end address of the bank > > belong to different sections. > > When gathering statictics of physical memory in mem_init() and > > show_mem(), this possiblity was not considered. > > Please write down the result if we doesn't consider this patch. > I can understand what happens but for making good description and review, > merging easily, it would be better to write down the result without > the patch explicitly.
You'll oops. __section_mem_map_addr() in:
> #define __pfn_to_page(pfn) \ > ({ unsigned long __pfn = (pfn); \ > struct mem_section *__sec = __pfn_to_section(__pfn); \ > __section_mem_map_addr(__sec) + __pfn; \ > })
will return NULL, you'll add some fuzz on to it with __pfn, then you'll oops when the arm show_mem() does PageReserved() and dereferences page->flags.
Ether that, or with the sparsemem vmemmap variant, you'll get a valid-looking pointer with no backing memory, and oops as well.
-- Dave
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