mm rmap: remove vma_address check for address inside vma

In file and anon rmap, we use interval trees to find potentially relevant
vmas and then call vma_address() to find the virtual address the given
page might be found at in these vmas.  vma_address() used to include a
check that the returned address falls within the limits of the vma, but
this check isn't necessary now that we always use interval trees in rmap:
the interval tree just doesn't return any vmas which this check would find
to be irrelevant.  As a result, we can replace the use of -EFAULT error
code (which then needed to be checked in every call site) with a
VM_BUG_ON().

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Santos <daniel.santos@pobox.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ce59ada0946263e8b1482d3249b73441905a1d14..7cf8b0ec11ecf29ef401e7dbeb8ac1084d692652 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1386,8 +1386,6 @@ static void __split_huge_page(struct page *page,
                struct vm_area_struct *vma = avc->vma;
                unsigned long addr = vma_address(page, vma);
                BUG_ON(is_vma_temporary_stack(vma));
-               if (addr == -EFAULT)
-                       continue;
                mapcount += __split_huge_page_splitting(page, vma, addr);
        }
        /*
@@ -1412,8 +1410,6 @@ static void __split_huge_page(struct page *page,
                struct vm_area_struct *vma = avc->vma;
                unsigned long addr = vma_address(page, vma);
                BUG_ON(is_vma_temporary_stack(vma));
-               if (addr == -EFAULT)
-                       continue;
                mapcount2 += __split_huge_page_map(page, vma, addr);
        }
        if (mapcount != mapcount2)

diff --git a/mm/rmap.c b/mm/rmap.c
index 9c61bf387fd1bc369638a3c33b5457f4bedb5ec0..28777412de62b166e65bc4c3503a0deeaf48ecd0 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -510,22 +510,26 @@ void page_unlock_anon_vma(struct anon_vma *anon_vma)
 
 /*
  * At what user virtual address is page expected in @vma?
- * Returns virtual address or -EFAULT if page's index/offset is not
- * within the range mapped the @vma.
  */
-inline unsigned long
-vma_address(struct page *page, struct vm_area_struct *vma)
+static inline unsigned long
+__vma_address(struct page *page, struct vm_area_struct *vma)
 {
        pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
-       unsigned long address;
 
        if (unlikely(is_vm_hugetlb_page(vma)))
                pgoff = page->index << huge_page_order(page_hstate(page));
-       address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
-       if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
-               /* page should be within @vma mapping range */
-               return -EFAULT;
-       }
+
+       return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+}
+
+inline unsigned long
+vma_address(struct page *page, struct vm_area_struct *vma)
+{
+       unsigned long address = __vma_address(page, vma);
+
+       /* page should be within @vma mapping range */
+       VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+
        return address;
 }
 
@@ -535,6 +539,7 @@ vma_address(struct page *page, struct vm_area_struct *vma)
  */
 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 {
+       unsigned long address;
        if (PageAnon(page)) {
                struct anon_vma *page__anon_vma = page_anon_vma(page);
                /*
@@ -550,7 +555,10 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
                        return -EFAULT;
        } else
                return -EFAULT;
-       return vma_address(page, vma);
+       address = __vma_address(page, vma);
+       if (unlikely(address < vma->vm_start || address >= vma->vm_end))
+               return -EFAULT;
+       return address;
 }
 
 /*
@@ -624,8 +632,8 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
        pte_t *pte;
        spinlock_t *ptl;
 
-       address = vma_address(page, vma);
-       if (address == -EFAULT)         /* out of vma range */
+       address = __vma_address(page, vma);
+       if (unlikely(address < vma->vm_start || address >= vma->vm_end))
                return 0;
        pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
        if (!pte)                       /* the page is not in this mm */
@@ -732,8 +740,6 @@ static int page_referenced_anon(struct page *page,
        anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
                struct vm_area_struct *vma = avc->vma;
                unsigned long address = vma_address(page, vma);
-               if (address == -EFAULT)
-                       continue;
                /*
                 * If we are reclaiming on behalf of a cgroup, skip
                 * counting on behalf of references from different
@@ -799,8 +805,6 @@ static int page_referenced_file(struct page *page,
 
        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                unsigned long address = vma_address(page, vma);
-               if (address == -EFAULT)
-                       continue;
                /*
                 * If we are reclaiming on behalf of a cgroup, skip
                 * counting on behalf of references from different
@@ -904,8 +908,6 @@ static int page_mkclean_file(struct address_space *mapping, struct page *page)
        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                if (vma->vm_flags & VM_SHARED) {
                        unsigned long address = vma_address(page, vma);
-                       if (address == -EFAULT)
-                               continue;
                        ret += page_mkclean_one(page, vma, address);
                }
        }
@@ -1468,8 +1470,6 @@ static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
                        continue;
 
                address = vma_address(page, vma);
-               if (address == -EFAULT)
-                       continue;
                ret = try_to_unmap_one(page, vma, address, flags);
                if (ret != SWAP_AGAIN || !page_mapped(page))
                        break;
@@ -1508,8 +1508,6 @@ static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
        mutex_lock(&mapping->i_mmap_mutex);
        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                unsigned long address = vma_address(page, vma);
-               if (address == -EFAULT)
-                       continue;
                ret = try_to_unmap_one(page, vma, address, flags);
                if (ret != SWAP_AGAIN || !page_mapped(page))
                        goto out;
@@ -1684,8 +1682,6 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
        anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
                struct vm_area_struct *vma = avc->vma;
                unsigned long address = vma_address(page, vma);
-               if (address == -EFAULT)
-                       continue;
                ret = rmap_one(page, vma, address, arg);
                if (ret != SWAP_AGAIN)
                        break;
@@ -1707,8 +1703,6 @@ static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *,
        mutex_lock(&mapping->i_mmap_mutex);
        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                unsigned long address = vma_address(page, vma);
-               if (address == -EFAULT)
-                       continue;
                ret = rmap_one(page, vma, address, arg);
                if (ret != SWAP_AGAIN)
                        break;