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Message-ID: <4865af61-7343-4c60-b4e2-f142f92b7c79@linux.dev>
Date: Tue, 12 Aug 2025 12:52:59 +0800
From: Lance Yang <lance.yang@...ux.dev>
To: David Hildenbrand <david@...hat.com>
Cc: linux-mm@...ck.org, xen-devel@...ts.xenproject.org,
linux-fsdevel@...r.kernel.org, nvdimm@...ts.linux.dev,
linuxppc-dev@...ts.ozlabs.org, Andrew Morton <akpm@...ux-foundation.org>,
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Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
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<sstabellini@...nel.org>,
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<willy@...radead.org>, Jan Kara <jack@...e.cz>,
Alexander Viro <viro@...iv.linux.org.uk>,
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Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka
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Alistair Popple <apopple@...dia.com>, Wei Yang <richard.weiyang@...il.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 01/11] mm/huge_memory: move more common code into
insert_pmd()
On 2025/8/11 19:26, David Hildenbrand wrote:
> Let's clean it all further up.
>
> No functional change intended.
>
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> Reviewed-by: Alistair Popple <apopple@...dia.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Reviewed-by: Wei Yang <richard.weiyang@...il.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
Nice. Feel free to add:
Reviewed-by: Lance Yang <lance.yang@...ux.dev>
Thanks,
Lance
> ---
> mm/huge_memory.c | 72 ++++++++++++++++--------------------------------
> 1 file changed, 24 insertions(+), 48 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 2b4ea5a2ce7d2..5314a89d676f1 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1379,15 +1379,25 @@ struct folio_or_pfn {
> bool is_folio;
> };
>
> -static int insert_pmd(struct vm_area_struct *vma, unsigned long addr,
> +static vm_fault_t insert_pmd(struct vm_area_struct *vma, unsigned long addr,
> pmd_t *pmd, struct folio_or_pfn fop, pgprot_t prot,
> - bool write, pgtable_t pgtable)
> + bool write)
> {
> struct mm_struct *mm = vma->vm_mm;
> + pgtable_t pgtable = NULL;
> + spinlock_t *ptl;
> pmd_t entry;
>
> - lockdep_assert_held(pmd_lockptr(mm, pmd));
> + if (addr < vma->vm_start || addr >= vma->vm_end)
> + return VM_FAULT_SIGBUS;
>
> + if (arch_needs_pgtable_deposit()) {
> + pgtable = pte_alloc_one(vma->vm_mm);
> + if (!pgtable)
> + return VM_FAULT_OOM;
> + }
> +
> + ptl = pmd_lock(mm, pmd);
> if (!pmd_none(*pmd)) {
> const unsigned long pfn = fop.is_folio ? folio_pfn(fop.folio) :
> fop.pfn;
> @@ -1395,15 +1405,14 @@ static int insert_pmd(struct vm_area_struct *vma, unsigned long addr,
> if (write) {
> if (pmd_pfn(*pmd) != pfn) {
> WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
> - return -EEXIST;
> + goto out_unlock;
> }
> entry = pmd_mkyoung(*pmd);
> entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
> if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
> update_mmu_cache_pmd(vma, addr, pmd);
> }
> -
> - return -EEXIST;
> + goto out_unlock;
> }
>
> if (fop.is_folio) {
> @@ -1424,11 +1433,17 @@ static int insert_pmd(struct vm_area_struct *vma, unsigned long addr,
> if (pgtable) {
> pgtable_trans_huge_deposit(mm, pmd, pgtable);
> mm_inc_nr_ptes(mm);
> + pgtable = NULL;
> }
>
> set_pmd_at(mm, addr, pmd, entry);
> update_mmu_cache_pmd(vma, addr, pmd);
> - return 0;
> +
> +out_unlock:
> + spin_unlock(ptl);
> + if (pgtable)
> + pte_free(mm, pgtable);
> + return VM_FAULT_NOPAGE;
> }
>
> /**
> @@ -1450,9 +1465,6 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, unsigned long pfn,
> struct folio_or_pfn fop = {
> .pfn = pfn,
> };
> - pgtable_t pgtable = NULL;
> - spinlock_t *ptl;
> - int error;
>
> /*
> * If we had pmd_special, we could avoid all these restrictions,
> @@ -1464,25 +1476,9 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, unsigned long pfn,
> (VM_PFNMAP|VM_MIXEDMAP));
> BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
>
> - if (addr < vma->vm_start || addr >= vma->vm_end)
> - return VM_FAULT_SIGBUS;
> -
> - if (arch_needs_pgtable_deposit()) {
> - pgtable = pte_alloc_one(vma->vm_mm);
> - if (!pgtable)
> - return VM_FAULT_OOM;
> - }
> -
> pfnmap_setup_cachemode_pfn(pfn, &pgprot);
>
> - ptl = pmd_lock(vma->vm_mm, vmf->pmd);
> - error = insert_pmd(vma, addr, vmf->pmd, fop, pgprot, write,
> - pgtable);
> - spin_unlock(ptl);
> - if (error && pgtable)
> - pte_free(vma->vm_mm, pgtable);
> -
> - return VM_FAULT_NOPAGE;
> + return insert_pmd(vma, addr, vmf->pmd, fop, pgprot, write);
> }
> EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
>
> @@ -1491,35 +1487,15 @@ vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio,
> {
> struct vm_area_struct *vma = vmf->vma;
> unsigned long addr = vmf->address & PMD_MASK;
> - struct mm_struct *mm = vma->vm_mm;
> struct folio_or_pfn fop = {
> .folio = folio,
> .is_folio = true,
> };
> - spinlock_t *ptl;
> - pgtable_t pgtable = NULL;
> - int error;
> -
> - if (addr < vma->vm_start || addr >= vma->vm_end)
> - return VM_FAULT_SIGBUS;
>
> if (WARN_ON_ONCE(folio_order(folio) != PMD_ORDER))
> return VM_FAULT_SIGBUS;
>
> - if (arch_needs_pgtable_deposit()) {
> - pgtable = pte_alloc_one(vma->vm_mm);
> - if (!pgtable)
> - return VM_FAULT_OOM;
> - }
> -
> - ptl = pmd_lock(mm, vmf->pmd);
> - error = insert_pmd(vma, addr, vmf->pmd, fop, vma->vm_page_prot,
> - write, pgtable);
> - spin_unlock(ptl);
> - if (error && pgtable)
> - pte_free(mm, pgtable);
> -
> - return VM_FAULT_NOPAGE;
> + return insert_pmd(vma, addr, vmf->pmd, fop, vma->vm_page_prot, write);
> }
> EXPORT_SYMBOL_GPL(vmf_insert_folio_pmd);
>
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