oom: fix integer overflow of points in oom_badness
[linux-2.6.git] / mm / pagewalk.c
index b4f27d2..2f5cf10 100644 (file)
@@ -1,26 +1,31 @@
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/sched.h>
+#include <linux/hugetlb.h>
 
 static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
-                         const struct mm_walk *walk, void *private)
+                         struct mm_walk *walk)
 {
        pte_t *pte;
        int err = 0;
 
        pte = pte_offset_map(pmd, addr);
-       do {
-               err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, private);
+       for (;;) {
+               err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
                if (err)
                       break;
-       } while (pte++, addr += PAGE_SIZE, addr != end);
+               addr += PAGE_SIZE;
+               if (addr == end)
+                       break;
+               pte++;
+       }
 
        pte_unmap(pte);
        return err;
 }
 
 static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
-                         const struct mm_walk *walk, void *private)
+                         struct mm_walk *walk)
 {
        pmd_t *pmd;
        unsigned long next;
@@ -28,18 +33,35 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 
        pmd = pmd_offset(pud, addr);
        do {
+again:
                next = pmd_addr_end(addr, end);
-               if (pmd_none_or_clear_bad(pmd)) {
+               if (pmd_none(*pmd)) {
                        if (walk->pte_hole)
-                               err = walk->pte_hole(addr, next, private);
+                               err = walk->pte_hole(addr, next, walk);
                        if (err)
                                break;
                        continue;
                }
+               /*
+                * This implies that each ->pmd_entry() handler
+                * needs to know about pmd_trans_huge() pmds
+                */
                if (walk->pmd_entry)
-                       err = walk->pmd_entry(pmd, addr, next, private);
-               if (!err && walk->pte_entry)
-                       err = walk_pte_range(pmd, addr, next, walk, private);
+                       err = walk->pmd_entry(pmd, addr, next, walk);
+               if (err)
+                       break;
+
+               /*
+                * Check this here so we only break down trans_huge
+                * pages when we _need_ to
+                */
+               if (!walk->pte_entry)
+                       continue;
+
+               split_huge_page_pmd(walk->mm, pmd);
+               if (pmd_none_or_clear_bad(pmd))
+                       goto again;
+               err = walk_pte_range(pmd, addr, next, walk);
                if (err)
                        break;
        } while (pmd++, addr = next, addr != end);
@@ -48,7 +70,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 }
 
 static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
-                         const struct mm_walk *walk, void *private)
+                         struct mm_walk *walk)
 {
        pud_t *pud;
        unsigned long next;
@@ -59,15 +81,15 @@ static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
                next = pud_addr_end(addr, end);
                if (pud_none_or_clear_bad(pud)) {
                        if (walk->pte_hole)
-                               err = walk->pte_hole(addr, next, private);
+                               err = walk->pte_hole(addr, next, walk);
                        if (err)
                                break;
                        continue;
                }
                if (walk->pud_entry)
-                       err = walk->pud_entry(pud, addr, next, private);
+                       err = walk->pud_entry(pud, addr, next, walk);
                if (!err && (walk->pmd_entry || walk->pte_entry))
-                       err = walk_pmd_range(pud, addr, next, walk, private);
+                       err = walk_pmd_range(pud, addr, next, walk);
                if (err)
                        break;
        } while (pud++, addr = next, addr != end);
@@ -75,31 +97,97 @@ static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
        return err;
 }
 
+#ifdef CONFIG_HUGETLB_PAGE
+static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
+                                      unsigned long end)
+{
+       unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
+       return boundary < end ? boundary : end;
+}
+
+static int walk_hugetlb_range(struct vm_area_struct *vma,
+                             unsigned long addr, unsigned long end,
+                             struct mm_walk *walk)
+{
+       struct hstate *h = hstate_vma(vma);
+       unsigned long next;
+       unsigned long hmask = huge_page_mask(h);
+       pte_t *pte;
+       int err = 0;
+
+       do {
+               next = hugetlb_entry_end(h, addr, end);
+               pte = huge_pte_offset(walk->mm, addr & hmask);
+               if (pte && walk->hugetlb_entry)
+                       err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+               if (err)
+                       return err;
+       } while (addr = next, addr != end);
+
+       return 0;
+}
+
+static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
+{
+       struct vm_area_struct *vma;
+
+       /* We don't need vma lookup at all. */
+       if (!walk->hugetlb_entry)
+               return NULL;
+
+       VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
+       vma = find_vma(walk->mm, addr);
+       if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma))
+               return vma;
+
+       return NULL;
+}
+
+#else /* CONFIG_HUGETLB_PAGE */
+static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk)
+{
+       return NULL;
+}
+
+static int walk_hugetlb_range(struct vm_area_struct *vma,
+                             unsigned long addr, unsigned long end,
+                             struct mm_walk *walk)
+{
+       return 0;
+}
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+
+
 /**
  * walk_page_range - walk a memory map's page tables with a callback
- * @mm - memory map to walk
- * @addr - starting address
- * @end - ending address
- * @walk - set of callbacks to invoke for each level of the tree
- * @private - private data passed to the callback function
+ * @mm: memory map to walk
+ * @addr: starting address
+ * @end: ending address
+ * @walk: set of callbacks to invoke for each level of the tree
  *
  * Recursively walk the page table for the memory area in a VMA,
  * calling supplied callbacks. Callbacks are called in-order (first
  * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
  * etc.). If lower-level callbacks are omitted, walking depth is reduced.
  *
- * Each callback receives an entry pointer, the start and end of the
- * associated range, and a caller-supplied private data pointer.
+ * Each callback receives an entry pointer and the start and end of the
+ * associated range, and a copy of the original mm_walk for access to
+ * the ->private or ->mm fields.
  *
- * No locks are taken, but the bottom level iterator will map PTE
+ * Usually no locks are taken, but splitting transparent huge page may
+ * take page table lock. And the bottom level iterator will map PTE
  * directories from highmem if necessary.
  *
  * If any callback returns a non-zero value, the walk is aborted and
  * the return value is propagated back to the caller. Otherwise 0 is returned.
+ *
+ * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
+ * is !NULL.
  */
-int walk_page_range(const struct mm_struct *mm,
-                   unsigned long addr, unsigned long end,
-                   const struct mm_walk *walk, void *private)
+int walk_page_range(unsigned long addr, unsigned long end,
+                   struct mm_walk *walk)
 {
        pgd_t *pgd;
        unsigned long next;
@@ -108,24 +196,52 @@ int walk_page_range(const struct mm_struct *mm,
        if (addr >= end)
                return err;
 
-       pgd = pgd_offset(mm, addr);
+       if (!walk->mm)
+               return -EINVAL;
+
+       pgd = pgd_offset(walk->mm, addr);
        do {
+               struct vm_area_struct *vma;
+
                next = pgd_addr_end(addr, end);
+
+               /*
+                * handle hugetlb vma individually because pagetable walk for
+                * the hugetlb page is dependent on the architecture and
+                * we can't handled it in the same manner as non-huge pages.
+                */
+               vma = hugetlb_vma(addr, walk);
+               if (vma) {
+                       if (vma->vm_end < next)
+                               next = vma->vm_end;
+                       /*
+                        * Hugepage is very tightly coupled with vma, so
+                        * walk through hugetlb entries within a given vma.
+                        */
+                       err = walk_hugetlb_range(vma, addr, next, walk);
+                       if (err)
+                               break;
+                       pgd = pgd_offset(walk->mm, next);
+                       continue;
+               }
+
                if (pgd_none_or_clear_bad(pgd)) {
                        if (walk->pte_hole)
-                               err = walk->pte_hole(addr, next, private);
+                               err = walk->pte_hole(addr, next, walk);
                        if (err)
                                break;
+                       pgd++;
                        continue;
                }
                if (walk->pgd_entry)
-                       err = walk->pgd_entry(pgd, addr, next, private);
+                       err = walk->pgd_entry(pgd, addr, next, walk);
                if (!err &&
                    (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
-                       err = walk_pud_range(pgd, addr, next, walk, private);
+                       err = walk_pud_range(pgd, addr, next, walk);
                if (err)
                        break;
-       } while (pgd++, addr = next, addr != end);
+               pgd++;
+       } while (addr = next, addr != end);
 
        return err;
 }