moreau francis wrote:
Alan Cox wrote:
Mapping out parts of a section is quite normal - think about the 640K to
1Mb hole in PC memory space.
OK. But I'm still worry. Please consider the following code
for (...; ...; ...) {
[...]
if (pfn_valid(i))
num_physpages++;
[...]
}
In that case num_physpages won't store an accurate value. Still it will be
used by the kernel to make some statistic assumptions on other kernel
data structure sizes.
That would be incorrect usage. pfn_valid() simply doesn't tell you if
you have memory backing a pfn, it mearly means you can interrogate the
page* for it. A good example of code which counts pages in a region is
in count_highmem_pages() which has a form as below:
for (pfn = start; pfn < end; pfn++) {
if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
if (PageReserved(page))
continue;
num_physpages++;
}
-apw
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