On Wed 25-10-17 08:27:35, Fan Du wrote:
> So user could check those interface for more detailed
> information about how much DAX mappings are currently
> created.
>
> Here we use vma_is_dax method to find specific page
> struture with DAX {huge, normal}page mappings,
> vm_normal_page routine works as before without any
> impact on the existing logical where _vm_normal_page
> are called.
>
> With this patch, user could check Device DAX usage at Ptes@ readings,
> fox example, statistics from a Device DAX algined by 2MB:
>
> 7f6c17800000-7f6c17e00000 rw-s 00000000 00:06 20559 /dev/dax12.0
> Size: 6144 kB
> .
> .
> .
> Ptes@2MB: 6144 kB
This says how but it doesn't tell why and who is going to use the
information and what for.
>
> Signed-off-by: Fan Du <fan.du@xxxxxxxxx>
> ---
> v3:
> * Elaborate more about the usage suggested by Michal Hocko
>
> v2:
> * Using pte_devmap to check valid pfn page structure,
> Pointed out by Dan. thx!
>
> ---
> fs/proc/task_mmu.c | 24 ++++++++++++++++++------
> 1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 30dbf37..5c4535c 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -531,7 +531,10 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
> struct page *page = NULL;
>
> if (pte_present(*pte)) {
> - page = vm_normal_page(vma, addr, *pte);
> + if (!vma_is_dax(vma))
> + page = vm_normal_page(vma, addr, *pte);
> + else if (pte_devmap(*pte))
> + page = pte_page(*pte);
> mss->rss_pte += PAGE_SIZE;
> } else if (is_swap_pte(*pte)) {
> swp_entry_t swpent = pte_to_swp_entry(*pte);
> @@ -583,7 +586,11 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
> struct page *page;
>
> /* FOLL_DUMP will return -EFAULT on huge zero page */
> - page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
> + if (!vma_is_dax(vma))
> + page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
> + else if (pmd_devmap(*pmd))
> + page = pmd_page(*pmd);
> +
> if (IS_ERR_OR_NULL(page))
> return;
> if (PageAnon(page))
> @@ -1770,13 +1777,15 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
> spinlock_t *ptl;
> pte_t *orig_pte;
> pte_t *pte;
> + struct page *page;
>
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> ptl = pmd_trans_huge_lock(pmd, vma);
> if (ptl) {
> - struct page *page;
> -
> - page = can_gather_numa_stats_pmd(*pmd, vma, addr);
> + if (!vma_is_dax(vma))
> + page = can_gather_numa_stats_pmd(*pmd, vma, addr);
> + else if (pmd_devmap(*pmd))
> + page = pmd_page(*pmd);
> if (page)
> gather_stats(page, md, pmd_dirty(*pmd),
> HPAGE_PMD_SIZE/PAGE_SIZE);
> @@ -1789,7 +1798,10 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
> #endif
> orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
> do {
> - struct page *page = can_gather_numa_stats(*pte, vma, addr);
> + if (!vma_is_dax(vma))
> + page = can_gather_numa_stats(*pte, vma, addr);
> + else if (pte_devmap(*pte))
> + page = pte_page(*pte);
> if (!page)
> continue;
> gather_stats(page, md, pte_dirty(*pte), 1);
> --
> 1.8.3.1
--
Michal Hocko
SUSE Labs
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