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-rw-r--r--mm/memory.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index af76397c2c54..56784e9a7151 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3317,6 +3317,43 @@ static int __do_fault(struct vm_area_struct *vma, unsigned long address,
return ret;
}
+static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmd,
+ pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
+{
+ struct page *fault_page;
+ spinlock_t *ptl;
+ pte_t entry, *pte;
+ int ret;
+
+ ret = __do_fault(vma, address, pgoff, flags, &fault_page);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ return ret;
+
+ pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+ if (unlikely(!pte_same(*pte, orig_pte))) {
+ pte_unmap_unlock(pte, ptl);
+ unlock_page(fault_page);
+ page_cache_release(fault_page);
+ return ret;
+ }
+
+ flush_icache_page(vma, fault_page);
+ entry = mk_pte(fault_page, vma->vm_page_prot);
+ if (pte_file(orig_pte) && pte_file_soft_dirty(orig_pte))
+ pte_mksoft_dirty(entry);
+ inc_mm_counter_fast(mm, MM_FILEPAGES);
+ page_add_file_rmap(fault_page);
+ set_pte_at(mm, address, pte, entry);
+
+ /* no need to invalidate: a not-present page won't be cached */
+ update_mmu_cache(vma, address, pte);
+ pte_unmap_unlock(pte, ptl);
+ unlock_page(fault_page);
+
+ return ret;
+}
+
/*
* do_fault() tries to create a new page mapping. It aggressively
* tries to share with existing pages, but makes a separate copy if
@@ -3510,6 +3547,9 @@ static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
pte_unmap(page_table);
+ if (!(flags & FAULT_FLAG_WRITE))
+ return do_read_fault(mm, vma, address, pmd, pgoff, flags,
+ orig_pte);
return do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
}
@@ -3542,6 +3582,9 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
}
pgoff = pte_to_pgoff(orig_pte);
+ if (!(flags & FAULT_FLAG_WRITE))
+ return do_read_fault(mm, vma, address, pmd, pgoff, flags,
+ orig_pte);
return do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
}