This is a 2.4 fix (not needed in 2.6): let's CC maintainer Willy Tarreau.
On Fri, 15 Sep 2006, Anatoli Antonovitch wrote:
> Description
> (max_mapnr << PAGE_SHIFT) would overflow on an x86 system which has more
> than 4GB memory, and hence cause vmap to fail every time.
Good point, thanks for the patch. Sorry I'm so slow to get to it.
>
> Signed-off-by: Michael Chen <[email protected]>
>
> Patch
> diff -Nur linux-2.4.21-40.EL/mm/vmalloc.c
> linux-2.4.21-40.EL.diff/mm/vmalloc.c
> --- linux-2.4.21-40.EL/mm/vmalloc.c 2006-02-02 21:13:20.000000000
> -0600
> +++ linux-2.4.21-40.EL.diff/mm/vmalloc.c 2006-09-04
And still needs fixing in latest mainline 2.4.
> 11:29:33.000000000 -0500
> @@ -298,8 +298,8 @@
> struct vm_struct *area;
> unsigned long size = count << PAGE_SHIFT;
>
> - if (!size || size > (max_mapnr << PAGE_SHIFT))
> - return NULL;
> + if (!count || count > max_mapnr)
> + return NULL;
I'm afraid the tabs got messed up in both the old and new lines.
Also, count is a signed int (whereas size and max_mapnr are both
unsigned longs), so best reject "count <= 0" rather than just "!count".
> area = get_vm_area(size, flags);
> if (!area) {
> return NULL;
Here's a replacement patch for Willy. Anatoli, you didn't sign
off the patch yourself: so I'm assuming Michael is the originator.
From: Michael Chen <[email protected]>
(max_mapnr << PAGE_SHIFT) would overflow on a system which has
4GB memory or more, and so could cause vmap to fail every time.
Signed-off-by: Michael Chen <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
---
mm/vmalloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 2.4.34-pre3/mm/vmalloc.c 2004-04-14 14:05:41.000000000 +0100
+++ linux/mm/vmalloc.c 2006-09-23 17:52:59.000000000 +0100
@@ -293,7 +293,7 @@ void * vmap(struct page **pages, int cou
struct vm_struct *area;
unsigned long size = count << PAGE_SHIFT;
- if (!size || size > (max_mapnr << PAGE_SHIFT))
+ if (count <= 0 || count > max_mapnr)
return NULL;
area = get_vm_area(size, flags);
if (!area) {
-
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