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Message-ID: <1bc0d2d8-567e-9fc1-39a5-ed498ad1d2d2@huawei.com>
Date: Mon, 18 Dec 2023 17:53:53 +0800
From: Nanyong Sun <sunnanyong@...wei.com>
To: Muchun Song <muchun.song@...ux.dev>
CC: <willy@...radead.org>, <wangkefeng.wang@...wei.com>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<linux-mm@...ck.org>, <catalin.marinas@....com>, <will@...nel.org>,
<mike.kravetz@...cle.com>, <akpm@...ux-foundation.org>,
<anshuman.khandual@....com>
Subject: Re: [PATCH 1/3] mm: HVO: introduce helper function to update and
flush pgtable
On 2023/12/15 11:36, Muchun Song wrote:
>
>
> On 2023/12/14 15:39, Nanyong Sun wrote:
>> Add pmd/pte update and tlb flush helper function to update page
>> table. This refactoring patch is designed to facilitate each
>> architecture to implement its own special logic in preparation
>> for the arm64 architecture to follow the necessary break-before-make
>> sequence when updating page tables.
>>
>> Signed-off-by: Nanyong Sun <sunnanyong@...wei.com>
>> ---
>> mm/hugetlb_vmemmap.c | 55 ++++++++++++++++++++++++++++++++++----------
>> 1 file changed, 43 insertions(+), 12 deletions(-)
>>
>> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
>> index 87818ee7f01d..49e8b351def3 100644
>> --- a/mm/hugetlb_vmemmap.c
>> +++ b/mm/hugetlb_vmemmap.c
>> @@ -45,6 +45,37 @@ struct vmemmap_remap_walk {
>> unsigned long flags;
>> };
>> +#ifndef vmemmap_update_pmd
>> +static inline void vmemmap_update_pmd(unsigned long start,
>> + pmd_t *pmd, pte_t *pgtable)
>> +{
>> + pmd_populate_kernel(&init_mm, pmd, pgtable);
>> +}
>> +#endif
>> +
>> +#ifndef vmemmap_update_pte
>> +static inline void vmemmap_update_pte(unsigned long addr,
>> + pte_t *pte, pte_t entry)
>> +{
>> + set_pte_at(&init_mm, addr, pte, entry);
>> +}
>> +#endif
>> +
>> +#ifndef flush_tlb_vmemmap_all
>> +static inline void flush_tlb_vmemmap_all(void)
>> +{
>> + flush_tlb_all();
>> +}
>> +#endif
>> +
>> +#ifndef flush_tlb_vmemmap_range
>> +static inline void flush_tlb_vmemmap_range(unsigned long start,
>> + unsigned long end)
>> +{
>> + flush_tlb_kernel_range(start, end);
>> +}
>> +#endif
>
> I'd like to rename both tlb-flush helpers to vmemmap_flush_tlb_all/range
> since other helpers all are prefixed with "vmemmap". It'll be more
> consistent for me.
>
> Otherwise LGTM. Thanks.
>
> Reviewed-by: Muchun Song <songmuchun@...edance.com>
Hi Muchun，
Thank you for your review on this patch set, I'll fix them and send out
the v2 version later.
>
>> +
>> static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start,
>> bool flush)
>> {
>> pmd_t __pmd;
>> @@ -87,9 +118,9 @@ static int split_vmemmap_huge_pmd(pmd_t *pmd,
>> unsigned long start, bool flush)
>> /* Make pte visible before pmd. See comment in
>> pmd_install(). */
>> smp_wmb();
>> - pmd_populate_kernel(&init_mm, pmd, pgtable);
>> + vmemmap_update_pmd(start, pmd, pgtable);
>> if (flush)
>> - flush_tlb_kernel_range(start, start + PMD_SIZE);
>> + flush_tlb_vmemmap_range(start, start + PMD_SIZE);
>> } else {
>> pte_free_kernel(&init_mm, pgtable);
>> }
>> @@ -217,7 +248,7 @@ static int vmemmap_remap_range(unsigned long
>> start, unsigned long end,
>> } while (pgd++, addr = next, addr != end);
>> if (walk->remap_pte && !(walk->flags &
>> VMEMMAP_REMAP_NO_TLB_FLUSH))
>> - flush_tlb_kernel_range(start, end);
>> + flush_tlb_vmemmap_range(start, end);
>> return 0;
>> }
>> @@ -263,15 +294,15 @@ static void vmemmap_remap_pte(pte_t *pte,
>> unsigned long addr,
>> /*
>> * Makes sure that preceding stores to the page contents from
>> - * vmemmap_remap_free() become visible before the set_pte_at()
>> - * write.
>> + * vmemmap_remap_free() become visible before the
>> + * vmemmap_update_pte() write.
>> */
>> smp_wmb();
>> }
>> entry = mk_pte(walk->reuse_page, pgprot);
>> list_add(&page->lru, walk->vmemmap_pages);
>> - set_pte_at(&init_mm, addr, pte, entry);
>> + vmemmap_update_pte(addr, pte, entry);
>> }
>> /*
>> @@ -310,10 +341,10 @@ static void vmemmap_restore_pte(pte_t *pte,
>> unsigned long addr,
>> /*
>> * Makes sure that preceding stores to the page contents become
>> visible
>> - * before the set_pte_at() write.
>> + * before the vmemmap_update_pte() write.
>> */
>> smp_wmb();
>> - set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot));
>> + vmemmap_update_pte(addr, pte, mk_pte(page, pgprot));
>> }
>> /**
>> @@ -576,7 +607,7 @@ long hugetlb_vmemmap_restore_folios(const struct
>> hstate *h,
>> }
>> if (restored)
>> - flush_tlb_all();
>> + flush_tlb_vmemmap_all();
>> if (!ret)
>> ret = restored;
>> return ret;
>> @@ -744,7 +775,7 @@ void hugetlb_vmemmap_optimize_folios(struct
>> hstate *h, struct list_head *folio_l
>> break;
>> }
>> - flush_tlb_all();
>> + flush_tlb_vmemmap_all();
>> list_for_each_entry(folio, folio_list, lru) {
>> int ret = __hugetlb_vmemmap_optimize_folio(h, folio,
>> @@ -760,7 +791,7 @@ void hugetlb_vmemmap_optimize_folios(struct
>> hstate *h, struct list_head *folio_l
>> * allowing more vmemmap remaps to occur.
>> */
>> if (ret == -ENOMEM && !list_empty(&vmemmap_pages)) {
>> - flush_tlb_all();
>> + flush_tlb_vmemmap_all();
>> free_vmemmap_page_list(&vmemmap_pages);
>> INIT_LIST_HEAD(&vmemmap_pages);
>> __hugetlb_vmemmap_optimize_folio(h, folio,
>> @@ -769,7 +800,7 @@ void hugetlb_vmemmap_optimize_folios(struct
>> hstate *h, struct list_head *folio_l
>> }
>> }
>> - flush_tlb_all();
>> + flush_tlb_vmemmap_all();
>> free_vmemmap_page_list(&vmemmap_pages);
>> }
>
> .
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