On 10/18/2012 03:20 PM, Andrew Morton wrote:
> On Wed, 17 Oct 2012 08:09:55 -0700
> Dave Hansen <dave@xxxxxxxxxxxxxxxxxx> wrote:
>>> +#ifdef CONFIG_MEMORY_FAILURE
>>> +static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
>>> +{
>>> + int i;
>>> +
>>> + if (!memmap)
>>> + return;
>>
>> I guess free_section_usemap() does the same thing.
>
> What does this observation mean?
sparse_remove_one_section() has an if(ms->section_mem_map) statement.
Inside that if() block is the only place in the function where 'memmap'
can get set.
Currently, sparse_remove_one_section() calls in to free_section_usemap()
ouside of that if() block. With this patch new call to
clear_hwpoisoned_pages() is done in the same place, both passing 'memmap'.
However, both free_section_usemap() and clear_hwpoisoned_pages() check
'memmap' for NULL and immediately return if so. That's a bit silly
since it could hide garbage coming back from sparse_decode_mem_map().
Seems like we should just call them both inside that if() block, or
reorganize sparse_remove_one_section(), maybe like this:
void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
{
struct page *memmap = NULL;
unsigned long *usemap = NULL;
if (!ms->section_mem_map)
return;
usemap = ms->pageblock_flags;
memmap = sparse_decode_mem_map(ms->section_mem_map,
__section_nr(ms));
ms->section_mem_map = 0;
ms->pageblock_flags = NULL;
free_section_usemap(memmap, usemap);
clear_hwpoisoned_pages(usemap, ...);
}
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