[PATCH] unpaged: VM_NONLINEAR VM_RESERVED

There's one peculiar use of VM_RESERVED which the previous patch left behind:
because VM_NONLINEAR's try_to_unmap_cluster uses vm_private_data as a swapout
cursor, but should never meet VM_RESERVED vmas, it was a way of extending
VM_NONLINEAR to VM_RESERVED vmas using vm_private_data for some other purpose.
 But that's an empty set - they don't have the populate function required.  So
just throw away those VM_RESERVED tests.

But one more interesting in rmap.c has to go too: try_to_unmap_one will want
to swap out an anonymous page from VM_RESERVED or VM_UNPAGED area.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 7 insertions, 14 deletions

diff --git a/mm/fremap.c b/mm/fremap.c
index 94254c5d7a18..007cbad9331e 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -204,12 +204,10 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
          * Make sure the vma is shared, that it supports prefaulting,
          * and that the remapped range is valid and fully within
          * the single existing vma.  vm_private_data is used as a
-         * swapout cursor in a VM_NONLINEAR vma (unless VM_RESERVED
-         * or VM_LOCKED, but VM_LOCKED could be revoked later on).
+         * swapout cursor in a VM_NONLINEAR vma.
          */
         if (vma && (vma->vm_flags & VM_SHARED) &&
-                (!vma->vm_private_data ||
-                        (vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) &&
+                (!vma->vm_private_data || (vma->vm_flags & VM_NONLINEAR)) &&
                 vma->vm_ops && vma->vm_ops->populate &&
                         end > start && start >= vma->vm_start &&
                                 end <= vma->vm_end) {
diff --git a/mm/rmap.c b/mm/rmap.c
index 914d04b98bee..377d417ec15f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -529,10 +529,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
          * If the page is mlock()d, we cannot swap it out.
          * If it's recently referenced (perhaps page_referenced
          * skipped over this mm) then we should reactivate it.
-         *
-         * Pages belonging to VM_RESERVED regions should not happen here.
          */
-        if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) ||
+        if ((vma->vm_flags & VM_LOCKED) ||
                         ptep_clear_flush_young(vma, address, pte)) {
                 ret = SWAP_FAIL;
                 goto out_unmap;
@@ -727,7 +725,7 @@ static int try_to_unmap_file(struct page *page)
 
         list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
                                                 shared.vm_set.list) {
-                if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
+                if (vma->vm_flags & VM_LOCKED)
                         continue;
                 cursor = (unsigned long) vma->vm_private_data;
                 if (cursor > max_nl_cursor)
@@ -761,7 +759,7 @@ static int try_to_unmap_file(struct page *page)
         do {
                 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
                                                 shared.vm_set.list) {
-                        if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
+                        if (vma->vm_flags & VM_LOCKED)
                                 continue;
                         cursor = (unsigned long) vma->vm_private_data;
                         while ( cursor < max_nl_cursor &&
@@ -783,11 +781,8 @@ static int try_to_unmap_file(struct page *page)
          * in locked vmas).  Reset cursor on all unreserved nonlinear
          * vmas, now forgetting on which ones it had fallen behind.
          */
-        list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
-                                                shared.vm_set.list) {
-                if (!(vma->vm_flags & VM_RESERVED))
-                        vma->vm_private_data = NULL;
-        }
+        list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
+                vma->vm_private_data = NULL;
 out:
         spin_unlock(&mapping->i_mmap_lock);
         return ret;