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Howlett" , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Muchun Song References: <20260819095140.17252-1-songmuchun@bytedance.com> <20260819095140.17252-9-songmuchun@bytedance.com> <178756196750.3606540.8562704442052486227.b4-review@b4> Content-Language: en-US From: Muchun Song In-Reply-To: <178756196750.3606540.8562704442052486227.b4-review@b4> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1396A180009 X-Stat-Signature: tpakiyd8mdk4r5s6erdajnjntepodjib X-Rspam-User: X-HE-Tag: 1787569805-571003 X-HE-Meta: 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 pkQHsyq3 /4x3xyWcklZak7ZliRrsjl9lndj5fXURBx16T4LjE3lP+nW1luPevpqZbeJYoGf2PRBqgEWB8dNQQvwLJjQmk0NgG86f99f7jjWnB/Bj2TvRQtG+1xVcsiQ7NVXmzkSL2QwqHwH76YRsGxBNYSaTlKGOzLbsqUvvL2hwKopDZzJXWFzbKz3BxucCQx/rQ/OrLnRxuDhnrViR1H7WLGF94bRClrxDpzKXdfID5g26pLGjURfN4a+SqbFlgCd7WvbAT7H9Qc54+qk/b/llx7AcGbjYB6KVyw6UgjadbTEJs8zCM5SqHvWk0sCsd1fQjE/z2EHSLICwCwqx4C10djXGbZVIQ1+a7LUNog0IULTdu7f44LpVtjRF3LOq9CzNhJOfD6+n2V0ULjvmt0bOx7JzZfVCSeR+OoWGAF3V4NsEbDtb1zaPZlgeyywDf0ojuopIj13eG4XA/mCCNXyM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026/8/24 16:59, Mike Rapoport wrote: >> Teach sparse-vmemmap population code to use the compound page order >> when deciding whether a vmemmap page can be optimized. >> >> With this information, the common sparse-vmemmap population path can >> allocate or reuse shared tail vmemmap pages directly instead of relying >> on HugeTLB-specific handling. >> >> This centralizes vmemmap optimization logic in the sparse-vmemmap code, >> based on section metadata, and prepares for sharing the same mechanism >> across different users of vmemmap optimization, including HugeTLB and >> DAX. >> >> Signed-off-by: Muchun Song >> >> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c >> index b770fe2428fd..737d50bdd3ef 100644 >> --- a/mm/sparse-vmemmap.c >> +++ b/mm/sparse-vmemmap.c >> @@ -186,6 +186,11 @@ static __meminit struct page *vmemmap_get_tail(unsigned int order, struct zone * >> >> return tail; >> } >> +#else >> +static inline struct page *vmemmap_get_tail(unsigned int order, struct zone *zone) >> +{ >> + return NULL; >> +} >> #endif >> >> static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node, >> @@ -193,12 +198,24 @@ static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in >> unsigned long ptpfn, unsigned long flags) >> { >> pte_t *pte = pte_offset_kernel(pmd, addr); >> + unsigned long pfn = page_to_pfn((struct page *)addr); >> + >> if (pte_none(ptep_get(pte))) { >> pte_t entry; >> - void *p; >> + >> + if (vmemmap_optimizable_pfn(pfn) && ptpfn == (unsigned long)-1) { >> + unsigned int order = pfn_to_section_order(pfn); >> + struct zone *zone = pfn_to_zone(pfn, node); >> + struct page *page = vmemmap_get_tail(order, zone); >> + >> + if (!page) >> + return NULL; >> + ptpfn = page_to_pfn(page); >> + } >> >> if (ptpfn == (unsigned long)-1) { >> - p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap); >> + void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap); >> + > What do you think about adding a helper function here, e.g something > like Better than mine. More clear. > > diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c > index 0aa0ab4f8b11..933b122f9937 100644 > --- a/mm/sparse-vmemmap.c > +++ b/mm/sparse-vmemmap.c > @@ -191,6 +191,23 @@ static inline struct page *vmemmap_get_tail(unsigned int order, struct zone *zon > } > #endif > > +static void * __meminit vmemmap_alloc_pte(unsigned long pfn, int node, > + struct vmem_altmap *altmap) > +{ > + unsigned int order = pfn_to_section_order(pfn); > + struct zone *zone = pfn_to_zone(pfn, node); > + struct page *page; > + > + if (!vmemmap_optimizable_pfn(pfn)) > + return vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap); > + > + page = vmemmap_get_tail(order, zone); > + if (!page) > + return NULL; > + > + return page_address(page); > +} > + > static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node, > struct vmem_altmap *altmap, > unsigned long ptpfn, unsigned long flags) > @@ -201,19 +218,8 @@ static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in > if (pte_none(ptep_get(pte))) { > pte_t entry; > > - if (vmemmap_optimizable_pfn(pfn) && ptpfn == (unsigned long)-1) { > - unsigned int order = pfn_to_section_order(pfn); > - struct zone *zone = pfn_to_zone(pfn, node); > - struct page *page = vmemmap_get_tail(order, zone); > - > - if (!page) > - return NULL; > - ptpfn = page_to_pfn(page); > - } > - > if (ptpfn == (unsigned long)-1) { > - void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap); > - > + void *p = vmemmap_alloc_pte(pfn, node, altmap); > if (!p) > return NULL; > ptpfn = PHYS_PFN(__pa(p)); > >> if (!p) >> return NULL; >> ptpfn = PHYS_PFN(__pa(p)); >> @@ -217,7 +234,8 @@ static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in >> } >> entry = pfn_pte(ptpfn, PAGE_KERNEL); >> set_pte_at(&init_mm, addr, pte, entry); >> - } >> + } else if (WARN_ON_ONCE(vmemmap_optimizable_pfn(pfn))) >> + return NULL; >> return pte; >> } >> >> @@ -406,6 +424,9 @@ int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end, >> pmd_t *pmd; >> >> for (addr = start; addr < end; addr = next) { >> + unsigned long pfn = page_to_pfn((struct page *)addr); >> + const struct mem_section *ms = __pfn_to_section(pfn); >> + >> next = pmd_addr_end(addr, end); >> >> pgd = vmemmap_pgd_populate(addr, node); >> @@ -421,7 +442,7 @@ int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end, >> return -ENOMEM; >> >> pmd = pmd_offset(pud, addr); >> - if (pmd_none(pmdp_get(pmd))) { >> + if (pmd_none(pmdp_get(pmd)) && !section_vmemmap_optimizable(ms)) { >> void *p; >> >> p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap); >> @@ -439,8 +460,11 @@ int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end, >> */ >> return -ENOMEM; >> } >> - } else if (vmemmap_check_pmd(pmd, node, addr, next)) >> + } else if (vmemmap_check_pmd(pmd, node, addr, next)) { >> + if (WARN_ON_ONCE(section_vmemmap_optimizable(ms))) >> + return -EOPNOTSUPP; >> continue; >> + } >> if (vmemmap_populate_basepages(addr, next, node, altmap)) >> return -ENOMEM; >> } >> @@ -620,6 +644,33 @@ void __init sparse_init_subsection_map(void) >> sparse_init_subsection_map_range(start, end - start); >> } >> >> +int __meminit section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages, >> + struct vmem_altmap *altmap, struct dev_pagemap *pgmap) >> +{ > Can we do all code movements in separate patches? Yes. > Maybe even move this to the previous patch and update the changelog to > say "move code around in preparation ..." Make sense. Will do next version. Muchun, Thanks.