UBUNTU: Ubuntu-4.10.0-37.41

[mirror_ubuntu-zesty-kernel.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 6bf2b471e30ca566a55160e4131bf7e7b9c3c4ea..6d54a9b1552077ee4c163936839c35ec92373b6b 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2714,40 +2714,6 @@ out_release:
        return ret;
 }
 
-/*
- * This is like a special single-page "expand_{down|up}wards()",
- * except we must first make sure that 'address{-|+}PAGE_SIZE'
- * doesn't hit another vma.
- */
-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
-{
-       address &= PAGE_MASK;
-       if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
-               struct vm_area_struct *prev = vma->vm_prev;
-
-               /*
-                * Is there a mapping abutting this one below?
-                *
-                * That's only ok if it's the same stack mapping
-                * that has gotten split..
-                */
-               if (prev && prev->vm_end == address)
-                       return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
-
-               return expand_downwards(vma, address - PAGE_SIZE);
-       }
-       if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
-               struct vm_area_struct *next = vma->vm_next;
-
-               /* As VM_GROWSDOWN but s/below/above/ */
-               if (next && next->vm_start == address + PAGE_SIZE)
-                       return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
-
-               return expand_upwards(vma, address + PAGE_SIZE);
-       }
-       return 0;
-}
-
 /*
  * We enter with non-exclusive mmap_sem (to exclude vma changes,
  * but allow concurrent faults), and pte mapped but not yet locked.
@@ -2764,10 +2730,6 @@ static int do_anonymous_page(struct vm_fault *vmf)
        if (vma->vm_flags & VM_SHARED)
                return VM_FAULT_SIGBUS;
 
-       /* Check if we need to add a guard page to the stack */
-       if (check_stack_guard_page(vma, vmf->address) < 0)
-               return VM_FAULT_SIGSEGV;
-
        /*
         * Use pte_alloc() instead of pte_alloc_map().  We can't run
         * pte_offset_map() on pmds where a huge pmd might be created
@@ -3387,32 +3349,32 @@ static int do_numa_page(struct vm_fault *vmf)
        int last_cpupid;
        int target_nid;
        bool migrated = false;
-       pte_t pte = vmf->orig_pte;
-       bool was_writable = pte_write(pte);
+       pte_t pte;
+       bool was_writable = pte_savedwrite(vmf->orig_pte);
        int flags = 0;
 
        /*
-       * The "pte" at this point cannot be used safely without
-       * validation through pte_unmap_same(). It's of NUMA type but
-       * the pfn may be screwed if the read is non atomic.
-       *
-       * We can safely just do a "set_pte_at()", because the old
-       * page table entry is not accessible, so there would be no
-       * concurrent hardware modifications to the PTE.
-       */
+        * The "pte" at this point cannot be used safely without
+        * validation through pte_unmap_same(). It's of NUMA type but
+        * the pfn may be screwed if the read is non atomic.
+        */
        vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
        spin_lock(vmf->ptl);
-       if (unlikely(!pte_same(*vmf->pte, pte))) {
+       if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
                pte_unmap_unlock(vmf->pte, vmf->ptl);
                goto out;
        }
 
-       /* Make it present again */
+       /*
+        * Make it present again, Depending on how arch implementes non
+        * accessible ptes, some can allow access by kernel mode.
+        */
+       pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
        pte = pte_modify(pte, vma->vm_page_prot);
        pte = pte_mkyoung(pte);
        if (was_writable)
                pte = pte_mkwrite(pte);
-       set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
+       ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
        update_mmu_cache(vma, vmf->address, vmf->pte);
 
        page = vm_normal_page(vma, vmf->address, pte);