VM, x86, PAT: Change is_linear_pfn_mapping to not use vm_pgoff
Impact: fix false positive PAT warnings - also fix VirtalBox hang
Use of vma->vm_pgoff to identify the pfnmaps that are fully
mapped at mmap time is broken. vm_pgoff is set by generic mmap
code even for cases where drivers are setting up the mappings
at the fault time.
The problem was originally reported here:
http://marc.info/?l=linux-kernel&m=123383810628583&w=2
Change is_linear_pfn_mapping logic to overload VM_INSERTPAGE
flag along with VM_PFNMAP to mean full PFNMAP setup at mmap
time.
Problem also tracked at:
http://bugzilla.kernel.org/show_bug.cgi?id=12800
Reported-by: Thomas Hellstrom <thellstrom@vmware.com>
Tested-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha>@intel.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: "ebiederm@xmission.com" <ebiederm@xmission.com>
Cc: <stable@kernel.org> # only for 2.6.29.1, not .28
LKML-Reference: <20090313004527.GA7176@linux-os.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/mm/memory.c b/mm/memory.c
index baa999e..d7df5ba 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1665,9 +1665,10 @@
* behaviour that some programs depend on. We mark the "original"
* un-COW'ed pages by matching them up with "vma->vm_pgoff".
*/
- if (addr == vma->vm_start && end == vma->vm_end)
+ if (addr == vma->vm_start && end == vma->vm_end) {
vma->vm_pgoff = pfn;
- else if (is_cow_mapping(vma->vm_flags))
+ vma->vm_flags |= VM_PFNMAP_AT_MMAP;
+ } else if (is_cow_mapping(vma->vm_flags))
return -EINVAL;
vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
@@ -1679,6 +1680,7 @@
* needed from higher level routine calling unmap_vmas
*/
vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
+ vma->vm_flags &= ~VM_PFNMAP_AT_MMAP;
return -EINVAL;
}