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

From: Jerome Marchand
Date: Wed Mar 01 2017 - 04:37:15 EST


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@xxxxxxxxxx>
> Cc: Khalid Aziz <khalid@xxxxxxxxxxxxxx>

This looks much better than your original version.

Acked-by: Jerome Marchand <jmarchan@xxxxxxxxxx>

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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