linux-kernel - Re: [PATCH v1 4/9] mm/memory: factor out zapping folio pte into zap_present_folio

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Message-ID: <e85fafb6-dd72-46c7-aa2c-2fa149f927d1@arm.com>
Date: Tue, 30 Jan 2024 08:47:34 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: David Hildenbrand <david@...hat.com>, linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
 Matthew Wilcox <willy@...radead.org>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
 Nick Piggin <npiggin@...il.com>, Peter Zijlstra <peterz@...radead.org>,
 Michael Ellerman <mpe@...erman.id.au>,
 Christophe Leroy <christophe.leroy@...roup.eu>,
 "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
 Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
 Alexander Gordeev <agordeev@...ux.ibm.com>,
 Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Sven Schnelle <svens@...ux.ibm.com>, Arnd Bergmann <arnd@...db.de>,
 linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 linux-s390@...r.kernel.org
Subject: Re: [PATCH v1 4/9] mm/memory: factor out zapping folio pte into
 zap_present_folio_pte()

On 29/01/2024 14:32, David Hildenbrand wrote:
> Let's prepare for further changes by factoring it out into a separate
> function.
> 
> Signed-off-by: David Hildenbrand <david@...hat.com>

Reviewed-by: Ryan Roberts <ryan.roberts@....com>

> ---
>  mm/memory.c | 53 ++++++++++++++++++++++++++++++++---------------------
>  1 file changed, 32 insertions(+), 21 deletions(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 20bc13ab8db2..a2190d7cfa74 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1528,30 +1528,14 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
>  	pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
>  }
>  
> -static inline void zap_present_pte(struct mmu_gather *tlb,
> -		struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
> -		unsigned long addr, struct zap_details *details,
> -		int *rss, bool *force_flush, bool *force_break)
> +static inline void zap_present_folio_pte(struct mmu_gather *tlb,
> +		struct vm_area_struct *vma, struct folio *folio,
> +		struct page *page, pte_t *pte, pte_t ptent, unsigned long addr,
> +		struct zap_details *details, int *rss, bool *force_flush,
> +		bool *force_break)
>  {
>  	struct mm_struct *mm = tlb->mm;
>  	bool delay_rmap = false;
> -	struct folio *folio;
> -	struct page *page;
> -
> -	page = vm_normal_page(vma, addr, ptent);
> -	if (!page) {
> -		/* We don't need up-to-date accessed/dirty bits. */
> -		ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
> -		arch_check_zapped_pte(vma, ptent);
> -		tlb_remove_tlb_entry(tlb, pte, addr);
> -		VM_WARN_ON_ONCE(userfaultfd_wp(vma));
> -		ksm_might_unmap_zero_page(mm, ptent);
> -		return;
> -	}
> -
> -	folio = page_folio(page);
> -	if (unlikely(!should_zap_folio(details, folio)))
> -		return;
>  
>  	if (!folio_test_anon(folio)) {
>  		ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
> @@ -1586,6 +1570,33 @@ static inline void zap_present_pte(struct mmu_gather *tlb,
>  	}
>  }
>  
> +static inline void zap_present_pte(struct mmu_gather *tlb,
> +		struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
> +		unsigned long addr, struct zap_details *details,
> +		int *rss, bool *force_flush, bool *force_break)
> +{
> +	struct mm_struct *mm = tlb->mm;
> +	struct folio *folio;
> +	struct page *page;
> +
> +	page = vm_normal_page(vma, addr, ptent);
> +	if (!page) {
> +		/* We don't need up-to-date accessed/dirty bits. */
> +		ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
> +		arch_check_zapped_pte(vma, ptent);
> +		tlb_remove_tlb_entry(tlb, pte, addr);
> +		VM_WARN_ON_ONCE(userfaultfd_wp(vma));
> +		ksm_might_unmap_zero_page(mm, ptent);
> +		return;
> +	}
> +
> +	folio = page_folio(page);
> +	if (unlikely(!should_zap_folio(details, folio)))
> +		return;
> +	zap_present_folio_pte(tlb, vma, folio, page, pte, ptent, addr, details,
> +			      rss, force_flush, force_break);
> +}
> +
>  static unsigned long zap_pte_range(struct mmu_gather *tlb,
>  				struct vm_area_struct *vma, pmd_t *pmd,
>  				unsigned long addr, unsigned long end,