Messages in this thread | | | Date | Fri, 24 Jun 2022 16:52:34 +0800 | Subject | Re: [RFC PATCH v2 2/3] mm: Add PUD level pagetable account | From | Baolin Wang <> |
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On 6/23/2022 9:28 PM, Matthew Wilcox wrote: > On Wed, Jun 22, 2022 at 09:38:30AM -0500, Mike Rapoport wrote: >> On Wed, Jun 22, 2022 at 04:58:53PM +0800, Baolin Wang wrote: >>> +++ b/arch/loongarch/include/asm/pgalloc.h >>> @@ -89,10 +89,15 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address) >>> static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address) >>> { >>> pud_t *pud; >>> + struct page *pg; >> >> struct page *page; >> >> looks better IMO. >> >>> + >>> + pg = alloc_pages(GFP_KERNEL & ~__GFP_HIGHMEM, PUD_ORDER); > > GFP_KERNEL does not include __GFP_HIGHMEM, so you can just use > GFP_KERNEL here.
Yes. Thanks.
> >>> + if (!pg) >>> + return NULL; >>> >>> - pud = (pud_t *) __get_free_pages(GFP_KERNEL, PUD_ORDER); >>> - if (pud) >>> - pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table); >>> + pgtable_set_and_inc(pg); >>> + pud = (pud_t *)page_address(pg); >> >> I don't think __get_free_pages() should be replaced with alloc_pages() >> here, just call pgtable_set_and_inc() with virt_to_page(pud). > > I don't understand why you want that. Take a look at the implementation > of __get_free_pages(). Converting back to a struct page after calling > that seems like a real waste of time to me.
IMO I have no strong preference. The code can be simpler with using __get_free_pages(), however like Matthew said it will add more conversion.
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