[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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Hugh Dickins 2005-11-21 21:32:12 -08:00 • committed by Linus Torvalds
commit 83e9b7e929
2 changed files with 0 additions and 19 deletions

View file

@ -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 "
"[email protected]\n",current->comm);
return -EACCES;
}
if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) {
charged = nrpages;
if (security_vm_enough_memory(charged))