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[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>
This commit is contained in:
Hugh Dickins 2005-11-21 21:32:12 -08:00 committed by Linus Torvalds
parent ed5297a940
commit 83e9b7e929
2 changed files with 0 additions and 19 deletions
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11
mm/mmap.c
View File

@ -1076,17 +1076,6 @@ munmap_back:
error = file->f_op->mmap(file, vma);
if (error)
goto unmap_and_free_vma;
if ((vma->vm_flags & (VM_SHARED | VM_WRITE | VM_RESERVED))
== (VM_WRITE | VM_RESERVED)) {
printk(KERN_WARNING "program %s is using MAP_PRIVATE, "
"PROT_WRITE mmap of VM_RESERVED memory, which "
"is deprecated. Please report this to "
"linux-kernel@vger.kernel.org\n",current->comm);
if (vma->vm_ops && vma->vm_ops->close)
vma->vm_ops->close(vma);
error = -EACCES;
goto unmap_and_free_vma;
}
} else if (vm_flags & VM_SHARED) {
error = shmem_zero_setup(vma);
if (error)

8
mm/mprotect.c
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 "
"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))