On Thu, Feb 01, 2024 at 04:05:40PM +0800, Qi Zheng wrote:
> For kernel PTE page, we do not need to allocate and initialize its split
> ptlock, but as a page table page, it's still necessary to add PG_table
> flag and NR_PAGETABLE statistics for it.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> ---
> include/asm-generic/pgalloc.h | 7 ++++++-
> include/linux/mm.h | 21 ++++++++++++++++-----
> 2 files changed, 22 insertions(+), 6 deletions(-)
This should also update the architectures that define
__HAVE_ARCH_PTE_ALLOC_ONE_KERNEL, otherwise NR_PAGETABLE counts will get
wrong.
Another related thing is that many architectures have custom allocations
for early page tables and these would also benefit form NR_PAGETABLE
accounting.
> diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
> index 879e5f8aa5e9..908bd9140ac2 100644
> --- a/include/asm-generic/pgalloc.h
> +++ b/include/asm-generic/pgalloc.h
> @@ -23,6 +23,8 @@ static inline pte_t *__pte_alloc_one_kernel(struct mm_struct *mm)
>
> if (!ptdesc)
> return NULL;
> +
> + __pagetable_pte_ctor(ptdesc);
> return ptdesc_address(ptdesc);
> }
>
> @@ -46,7 +48,10 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
> */
> static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
> {
> - pagetable_free(virt_to_ptdesc(pte));
> + struct ptdesc *ptdesc = virt_to_ptdesc(pte);
> +
> + __pagetable_pte_dtor(ptdesc);
> + pagetable_free(ptdesc);
> }
>
> /**
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index e442fd0efdd9..e37db032764e 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2922,26 +2922,37 @@ static inline bool ptlock_init(struct ptdesc *ptdesc) { return true; }
> static inline void ptlock_free(struct ptdesc *ptdesc) {}
> #endif /* USE_SPLIT_PTE_PTLOCKS */
>
> -static inline bool pagetable_pte_ctor(struct ptdesc *ptdesc)
> +static inline void __pagetable_pte_ctor(struct ptdesc *ptdesc)
> {
> struct folio *folio = ptdesc_folio(ptdesc);
>
> - if (!ptlock_init(ptdesc))
> - return false;
> __folio_set_pgtable(folio);
> lruvec_stat_add_folio(folio, NR_PAGETABLE);
> +}
> +
> +static inline bool pagetable_pte_ctor(struct ptdesc *ptdesc)
> +{
> + if (!ptlock_init(ptdesc))
> + return false;
> +
> + __pagetable_pte_ctor(ptdesc);
> return true;
> }
>
> -static inline void pagetable_pte_dtor(struct ptdesc *ptdesc)
> +static inline void __pagetable_pte_dtor(struct ptdesc *ptdesc)
> {
> struct folio *folio = ptdesc_folio(ptdesc);
>
> - ptlock_free(ptdesc);
> __folio_clear_pgtable(folio);
> lruvec_stat_sub_folio(folio, NR_PAGETABLE);
> }
>
> +static inline void pagetable_pte_dtor(struct ptdesc *ptdesc)
> +{
> + ptlock_free(ptdesc);
> + __pagetable_pte_dtor(ptdesc);
> +}
> +
> pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp);
> static inline pte_t *pte_offset_map(pmd_t *pmd, unsigned long addr)
> {
> --
> 2.30.2
>
>
--
Sincerely yours,
Mike.
