[PATCH 3/4] Hugetlb: Reorganize hugetlb_fault to prepare for COW
From: Adam Litke <hidden>
Date: 2005-11-09 23:39:40
Also in:
lkml
This patch splits the "no_page()" type activity into its own function, hugetlb_no_page(). hugetlb_fault() becomes the entry point for hugetlb faults and delegates to the appropriate handler depending on the type of fault. Right now we still have only hugetlb_no_page() but a later patch introduces a COW fault. Original post by David Gibson [off-list ref] Version 2: Wed 9 Nov 2005 Broken out into a separate patch Signed-off-by: David Gibson <redacted> Signed-off-by: Adam Litke <redacted> --- hugetlb.c | 34 +++++++++++++++++++++++++--------- 1 files changed, 25 insertions(+), 9 deletions(-) diff -upN reference/mm/hugetlb.c current/mm/hugetlb.c
--- reference/mm/hugetlb.c
+++ current/mm/hugetlb.c@@ -370,20 +370,15 @@ out: return page; } -int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long address, int write_access) +int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, pte_t *ptep) { int ret = VM_FAULT_SIGBUS; unsigned long idx; unsigned long size; - pte_t *pte; struct page *page; struct address_space *mapping; - pte = huge_pte_alloc(mm, address); - if (!pte) - goto out; - mapping = vma->vm_file->f_mapping; idx = ((address - vma->vm_start) >> HPAGE_SHIFT) + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
@@ -402,11 +397,11 @@ int hugetlb_fault(struct mm_struct *mm, goto backout; ret = VM_FAULT_MINOR; - if (!pte_none(*pte)) + if (!pte_none(*ptep)) goto backout; add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE); - set_huge_pte_at(mm, address, pte, make_huge_pte(vma, page)); + set_huge_pte_at(mm, address, ptep, make_huge_pte(vma, page)); spin_unlock(&mm->page_table_lock); unlock_page(page); out:
@@ -420,6 +415,27 @@ backout: goto out; } +int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, int write_access) +{ + pte_t *ptep; + pte_t entry; + + ptep = huge_pte_alloc(mm, address); + if (!ptep) + return VM_FAULT_OOM; + + entry = *ptep; + if (pte_none(entry)) + return hugetlb_no_page(mm, vma, address, ptep); + + /* + * We could get here if another thread instantiated the pte + * before the test above. + */ + return VM_FAULT_MINOR; +} + int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, struct page **pages, struct vm_area_struct **vmas, unsigned long *position, int *length, int i)
--
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center
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