On 03/26/2013 03:48 AM, Kirill A. Shutemov wrote:
> Dave Hansen wrote:
>>> +repeat:
>>> + page = find_lock_page(mapping, index);
>>> + if (page) {
>>> + if (!PageTransHuge(page)) {
>>> + unlock_page(page);
>>> + page_cache_release(page);
>>> + return NULL;
>>> + }
>>> + goto found;
>>> + }
>>> +
>>> + page = alloc_pages(gfp_mask & ~gfp_notmask, HPAGE_PMD_ORDER);
>>
>> I alluded to this a second ago, but what's wrong with alloc_hugepage()?
>
> It's defined only for !CONFIG_NUMA and only inside mm/huge_memory.c.
It's a short function, but you could easily pull it out from under the
#ifdef and export it. I kinda like the idea of these things being
allocated in as few code paths possible. But, it's not a big deal.
>>> +found:
>>> + wait_on_page_writeback(page);
>>> + return page;
>>> +}
>>> +#endif
>>
>> So, I diffed :
>>
>> -struct page *grab_cache_page_write_begin(struct address_space
>> vs.
>> +struct page *grab_cache_huge_page_write_begin(struct address_space
>>
>> They're just to similar to ignore. Please consolidate them somehow.
>
> Will do.
>
>>> +found:
>>> + wait_on_page_writeback(page);
>>> + return page;
>>> +}
>>> +#endif
>>
>> In grab_cache_page_write_begin(), this "wait" is:
>>
>> wait_for_stable_page(page);
>>
>> Why is it different here?
>
> It was wait_on_page_writeback() in grab_cache_page_write_begin() when I forked
> it :(
>
> See 1d1d1a7 mm: only enforce stable page writes if the backing device
> requires it
>
> Consolidation will fix this.
Excellent.
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