get_user_pages: don't try to follow PFNMAP pages

Nick Piggin points out that a few drivers play games with VM_IO (why?
who knows..) and thus a pfn-remapped area may not have that bit set even
if remap_pfn_range() set it originally.

So make it explicit in get_user_pages() that we don't follow VM_PFNMAP
pages, since pretty much by definition they do not have a "struct page"
associated with them.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 47c533eaa072..d22f78c8a381 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1009,7 +1009,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                         continue;
                 }
 
-                if (!vma || (vma->vm_flags & VM_IO)
+                if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
                                 || !(vm_flags & vma->vm_flags))
                         return i ? : -EFAULT;