| Message ID | 20200110190313.17144-3-joao.m.martins@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC,01/10] mm: Add pmd support for _PAGE_SPECIAL | expand |
On Fri, Jan 10, 2020 at 07:03:05PM +0000, Joao Martins wrote: > @@ -4366,6 +4366,7 @@ EXPORT_SYMBOL(follow_pte_pmd); > int follow_pfn(struct vm_area_struct *vma, unsigned long address, > unsigned long *pfn) > { > + pmd_t *pmdpp = NULL; Please rename to 'pmdp'.
On 2/3/20 9:37 PM, Matthew Wilcox wrote: > On Fri, Jan 10, 2020 at 07:03:05PM +0000, Joao Martins wrote: >> @@ -4366,6 +4366,7 @@ EXPORT_SYMBOL(follow_pte_pmd); >> int follow_pfn(struct vm_area_struct *vma, unsigned long address, >> unsigned long *pfn) >> { >> + pmd_t *pmdpp = NULL; > > Please rename to 'pmdp'. > Will do. Alongside patch 4 usage of pmdpp and renaming 'pudpp' to 'pudp'.
diff --git a/mm/memory.c b/mm/memory.c index cfc3668bddeb..db99684d2cb3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4366,6 +4366,7 @@ EXPORT_SYMBOL(follow_pte_pmd); int follow_pfn(struct vm_area_struct *vma, unsigned long address, unsigned long *pfn) { + pmd_t *pmdpp = NULL; int ret = -EINVAL; spinlock_t *ptl; pte_t *ptep; @@ -4373,10 +4374,14 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address, if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) return ret; - ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); + ret = follow_pte_pmd(vma->vm_mm, address, NULL, + &ptep, &pmdpp, &ptl); if (ret) return ret; - *pfn = pte_pfn(*ptep); + if (pmdpp) + *pfn = pmd_pfn(*pmdpp) + ((address & ~PMD_MASK) >> PAGE_SHIFT); + else + *pfn = pte_pfn(*ptep); pte_unmap_unlock(ptep, ptl); return 0; }
When follow_pfn hits a pmd_huge() it won't return a valid PFN given it's usage of follow_pte(). Fix that up to pass a @pmdpp and thus allow callers to get the pmd pointer. If we encounter such a huge page, we calculate the pfn offset to the PMD accordingly. This allows KVM to handle 2M hugepage pfns on VM_PFNMAP vmas. Signed-off-by: Joao Martins <joao.m.martins@oracle.com> --- mm/memory.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)