Re: [PATCH v6 2/4] mm: Add functions to support extra actions on swap in/out

[Jerome Marchand <jmarchan@redhat.com>]

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On 02/28/2017 07:35 PM, Khalid Aziz wrote:
> If a processor supports special metadata for a page, for example ADI
> version tags on SPARC M7, this metadata must be saved when the page is
> swapped out. The same metadata must be restored when the page is swapped
> back in. This patch adds two new architecture specific functions -
> arch_do_swap_page() to be called when a page is swapped in,
> arch_unmap_one() to be called when a page is being unmapped for swap
> out.
> 
> Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
> Cc: Khalid Aziz <khalid@gonehiking.org>

This looks much better than your original version.

Acked-by: Jerome Marchand <jmarchan@redhat.com>

Thanks,
Jerome

> ---
> v5:
> 	- Replaced set_swp_pte() function with new architecture
> 	  functions arch_do_swap_page() and arch_unmap_one()
> 
>  include/asm-generic/pgtable.h | 16 ++++++++++++++++
>  mm/memory.c                   |  1 +
>  mm/rmap.c                     |  2 ++
>  3 files changed, 19 insertions(+)
> 
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 18af2bc..5764d8f 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -282,6 +282,22 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  #endif
>  
> +#ifndef __HAVE_ARCH_DO_SWAP_PAGE
> +static inline void arch_do_swap_page(struct mm_struct *mm, unsigned long addr,
> +				     pte_t pte, pte_t orig_pte)
> +{
> +
> +}
> +#endif
> +
> +#ifndef __HAVE_ARCH_UNMAP_ONE
> +static inline void arch_unmap_one(struct mm_struct *mm, unsigned long addr,
> +				  pte_t pte, pte_t orig_pte)
> +{
> +
> +}
> +#endif
> +
>  #ifndef __HAVE_ARCH_PGD_OFFSET_GATE
>  #define pgd_offset_gate(mm, addr)	pgd_offset(mm, addr)
>  #endif
> diff --git a/mm/memory.c b/mm/memory.c
> index 6bf2b47..b086c76 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2658,6 +2658,7 @@ int do_swap_page(struct vm_fault *vmf)
>  	if (pte_swp_soft_dirty(vmf->orig_pte))
>  		pte = pte_mksoft_dirty(pte);
>  	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
> +	arch_do_swap_page(vma->vm_mm, vmf->address, pte, vmf->orig_pte);
>  	vmf->orig_pte = pte;
>  	if (page == swapcache) {
>  		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 91619fd..192c41a 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1538,6 +1538,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  		swp_pte = swp_entry_to_pte(entry);
>  		if (pte_soft_dirty(pteval))
>  			swp_pte = pte_swp_mksoft_dirty(swp_pte);
> +		arch_unmap_one(mm, address, swp_pte, pteval);
>  		set_pte_at(mm, address, pte, swp_pte);
>  	} else if (PageAnon(page)) {
>  		swp_entry_t entry = { .val = page_private(page) };
> @@ -1571,6 +1572,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  		swp_pte = swp_entry_to_pte(entry);
>  		if (pte_soft_dirty(pteval))
>  			swp_pte = pte_swp_mksoft_dirty(swp_pte);
> +		arch_unmap_one(mm, address, swp_pte, pteval);
>  		set_pte_at(mm, address, pte, swp_pte);
>  	} else
>  		dec_mm_counter(mm, mm_counter_file(page));
> 



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