* [PATCH v3] mm/page_vma_mapped.c: Explicitly compare pfn for noraml, hugetlbfs and THP page
@ 2020-01-10 15:56 Li Xinhai
2020-01-11 0:00 ` Kirill A. Shutemov
0 siblings, 1 reply; 2+ messages in thread
From: Li Xinhai @ 2020-01-10 15:56 UTC (permalink / raw)
To: linux-mm; +Cc: Kirill A. Shutemov, Mike Kravetz, Michal Hocko
When check_pte, pfn of normal, hugetlbfs and THP page need be compared.
The current implementation apply comparison as
- normal page: page_pfn <= pfn < page_pfn + 1
- hugetlbfs page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR
- THP page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR
in pfn_in_hpage. For hugetlbfs page, it should be
page_pfn == pfn
Now, change pfn_in_hpage to pfn_is_match to highlight that comparison
is not only for THP and explicitly compare for these cases.
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
---
mm/page_vma_mapped.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index eff4b45..a286ff7 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -52,12 +52,16 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw)
return true;
}
-static inline bool pfn_in_hpage(struct page *hpage, unsigned long pfn)
+static inline bool pfn_is_match(struct page *page, unsigned long pfn)
{
- unsigned long hpage_pfn = page_to_pfn(hpage);
+ unsigned long page_pfn = page_to_pfn(page);
+
+ /* normal page and hugetlbfs page */
+ if (!PageCompound(page) || PageHuge(page))
+ return page_pfn == pfn;
/* THP can be referenced by any subpage */
- return pfn >= hpage_pfn && pfn - hpage_pfn < hpage_nr_pages(hpage);
+ return pfn >= page_pfn && pfn - page_pfn < hpage_nr_pages(page);
}
/**
@@ -108,7 +112,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
pfn = pte_pfn(*pvmw->pte);
}
- return pfn_in_hpage(pvmw->page, pfn);
+ return pfn_is_match(pvmw->page, pfn);
}
/**
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3] mm/page_vma_mapped.c: Explicitly compare pfn for noraml, hugetlbfs and THP page
2020-01-10 15:56 [PATCH v3] mm/page_vma_mapped.c: Explicitly compare pfn for noraml, hugetlbfs and THP page Li Xinhai
@ 2020-01-11 0:00 ` Kirill A. Shutemov
0 siblings, 0 replies; 2+ messages in thread
From: Kirill A. Shutemov @ 2020-01-11 0:00 UTC (permalink / raw)
To: Li Xinhai; +Cc: linux-mm, Kirill A. Shutemov, Mike Kravetz, Michal Hocko
On Fri, Jan 10, 2020 at 03:56:44PM +0000, Li Xinhai wrote:
> When check_pte, pfn of normal, hugetlbfs and THP page need be compared.
> The current implementation apply comparison as
> - normal page: page_pfn <= pfn < page_pfn + 1
> - hugetlbfs page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR
> - THP page: page_pfn <= pfn < page_pfn + HPAGE_PMD_NR
> in pfn_in_hpage. For hugetlbfs page, it should be
> page_pfn == pfn
>
> Now, change pfn_in_hpage to pfn_is_match to highlight that comparison
> is not only for THP and explicitly compare for these cases.
>
> Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Michal Hocko <mhocko@kernel.org>
> ---
> mm/page_vma_mapped.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index eff4b45..a286ff7 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -52,12 +52,16 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw)
> return true;
> }
>
> -static inline bool pfn_in_hpage(struct page *hpage, unsigned long pfn)
> +static inline bool pfn_is_match(struct page *page, unsigned long pfn)
> {
> - unsigned long hpage_pfn = page_to_pfn(hpage);
> + unsigned long page_pfn = page_to_pfn(page);
> +
> + /* normal page and hugetlbfs page */
> + if (!PageCompound(page) || PageHuge(page))
!PageTransCompound() instead of !PageCompound() would be better for cases
when THP is disabled compile-time. Otherwise:
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-01-10 15:56 [PATCH v3] mm/page_vma_mapped.c: Explicitly compare pfn for noraml, hugetlbfs and THP page Li Xinhai
2020-01-11 0:00 ` Kirill A. Shutemov
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