On Tue 14-01-20 21:47:51, Li Xinhai wrote: > On 2020-01-14 at 17:25 Michal Hocko wrote: > >On Sat 11-01-20 10:18:05, Li Xinhai wrote: > >> When check_pte, pfn of normal, hugetlbfs and THP page need be compared. > >> The current implementation apply comparison as > >> - normal 4K page: page_pfn <= pfn < page_pfn + 1 > >> - hugetlbfs page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR > >> - THP page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR > >> in pfn_in_hpage. For hugetlbfs page, it should be > >> page_pfn == pfn > >> > >> Now, change pfn_in_hpage to pfn_is_match to highlight that comparison > >> is not only for THP and explicitly compare for these cases. > > > >Why is this important to do. I have asked and Mike had the same feeling > >that the patch is missing any real justification. Why do we need this > >change? It is great that you have dropped VM_BUG_ON btw. > > > I think it is important to make the code clear, as said, comparing hugetlbfs page > in range page_pfn <= pfn < page_pfn + HPAGE_PMD_NR is confusion. I am sorry but I do not really see a big confusion here. It is probably a matter of taste. If others consider this an improvement then I will not stand in the way but I consider the justification insuficient for merging. -- Michal Hocko SUSE Labs
