[PATCH] unpaged: private write VM_RESERVED

The PageReserved removal in 2.6.15-rc1 issued a "deprecated" message when you
tried to mmap or mprotect MAP_PRIVATE PROT_WRITE a VM_RESERVED, and failed
with -EACCES: because do_wp_page lacks the refinement to COW pages in those
areas, nor do we expect to find anonymous pages in them; and it seemed just
bloat to add code for handling such a peculiar case.  But immediately it
caused vbetool and ddcprobe (using lrmi) to fail.

So revert the "deprecated" messages, letting mmap and mprotect succeed.  But
leave do_wp_page's BUG_ON(vma->vm_flags & VM_RESERVED) in place until we've
added the code to do it right: so this particular patch is only good if the
app doesn't really need to write to that private 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>

1 files changed, 0 insertions, 8 deletions

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 17a2b52b753b..653b8571c1ed 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -124,14 +124,6 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
          * a MAP_NORESERVE private mapping to writable will now reserve.
          */
         if (newflags & VM_WRITE) {
-                if (oldflags & VM_RESERVED) {
-                        BUG_ON(oldflags & VM_WRITE);
-                        printk(KERN_WARNING "program %s is using MAP_PRIVATE, "
-                                "PROT_WRITE mprotect of VM_RESERVED memory, "
-                                "which is deprecated. Please report this to "
-                                "linux-kernel@vger.kernel.org\n",current->comm);
-                        return -EACCES;
-                }
                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) {
                         charged = nrpages;
                         if (security_vm_enough_memory(charged))