-stable review patch. If anyone has any objections, please let us know.
------------------
From: Linus Torvalds <[email protected]>
This reverts commit 99a10a60ba9bedcf5d70ef81414d3e03816afa3f.
As per Hugh Dickins:
"Nadia Derbey has reported that mmap of /dev/kmem no longer works with
the kernel virtual address as offset, and Franck has confirmed that
his patch came from a misunderstanding of what an offset means to
/dev/kmem - whereas his patch description seems to say that he was
correcting the offset on a few plaforms, there was no such problem to
correct, and his patch was in fact changing its API on all platforms."
Suggested-by: Hugh Dickins <[email protected]>
Cc: Franck Bui-Huu <[email protected]>
Cc: Nadia Derbey <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---
drivers/char/mem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- linux-2.6.19.2.orig/drivers/char/mem.c
+++ linux-2.6.19.2/drivers/char/mem.c
@@ -293,8 +293,8 @@ static int mmap_kmem(struct file * file,
{
unsigned long pfn;
- /* Turn a pfn offset into an absolute pfn */
- pfn = PFN_DOWN(virt_to_phys((void *)PAGE_OFFSET)) + vma->vm_pgoff;
+ /* Turn a kernel-virtual address into a physical page frame */
+ pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
/*
* RED-PEN: on some architectures there is more mapped memory
--