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charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Nov 10, 2020 at 1:42 PM Oscar Salvador wrote: > > On Tue, Nov 10, 2020 at 11:49:27AM +0800, Muchun Song wrote: > > On Tue, Nov 10, 2020 at 1:21 AM Oscar Salvador wrote: > > > > > > On Sun, Nov 08, 2020 at 10:10:57PM +0800, Muchun Song wrote: > > > > +static inline unsigned int pgtable_pages_to_prealloc_per_hpage(struct hstate *h) > > > > +{ > > > > + unsigned long vmemmap_size = vmemmap_pages_size_per_hpage(h); > > > > + > > > > + /* > > > > + * No need pre-allocate page tabels when there is no vmemmap pages > > > > + * to free. > > > s /tabels/tables/ > > > > Thanks. > > > > > > > > > +static int vmemmap_pgtable_prealloc(struct hstate *h, struct page *page) > > > > +{ > > > > + int i; > > > > + pgtable_t pgtable; > > > > + unsigned int nr = pgtable_pages_to_prealloc_per_hpage(h); > > > > + > > > > + if (!nr) > > > > + return 0; > > > > + > > > > + vmemmap_pgtable_init(page); > > > > + > > > > + for (i = 0; i < nr; i++) { > > > > + pte_t *pte_p; > > > > + > > > > + pte_p = pte_alloc_one_kernel(&init_mm); > > > > + if (!pte_p) > > > > + goto out; > > > > + vmemmap_pgtable_deposit(page, virt_to_page(pte_p)); > > > > + } > > > > + > > > > + return 0; > > > > +out: > > > > + while (i-- && (pgtable = vmemmap_pgtable_withdraw(page))) > > > > + pte_free_kernel(&init_mm, page_to_virt(pgtable)); > > > > > > would not be enough to: > > > > > > while (pgtable = vmemmap_pgtable_withdrag(page)) > > > pte_free_kernel(&init_mm, page_to_virt(pgtable)); > > > > The vmemmap_pgtable_withdraw can not return NULL. So we can not > > drop the "i--". > > Yeah, you are right, I managed to confuse myself. > But why not make it return null, something like: > > static pgtable_t vmemmap_pgtable_withdraw(struct page *page) > { > pgtable_t pgtable; > > /* FIFO */ > pgtable = page_huge_pte(page); The check should be added here. if (!pgtable) return NULL; Just like my previous v2 patch does. In this case, we can drop those checks. What do you think? > page_huge_pte(page) = list_first_entry_or_null(&pgtable->lru, > struct page, lru); > if (page_huge_pte(page)) > list_del(&pgtable->lru); > > return page_huge_pte(page) ? pgtable : NULL; > } > > What do you think? > > > -- > Oscar Salvador > SUSE L3 -- Yours, Muchun