Re: [PATCH 1/4] pagemap: Require reads of /proc/pid/pagemap to be multiples of 8 (v2 of series)

[Matt Mackall <mpm@selenic.com>]

On Thu, 2008-06-05 at 12:37 -0700, Andrew Morton wrote:
> On Thu, 5 Jun 2008 14:38:10 -0400
> "Thomas Tuttle" <ttuttle@google.com> wrote:
> 
> > This matches the behavior of /proc/kpage{count,flags}, and simplifies
> > the logic a bit.
> > 
> > I also changed out and end in struct pagemapread to be u64* instead of
> > char*, which makes put_user work the way it was intended.  (Before, it
> > was only copying the bottom byte of a pagemap entry, because the target
> > of the copy was a char*.)
> 
> This one is for 2.6.25.x?

This one is for 2.6.26. Something more like this for 2.6.25.x:

Because put_user bases its copy size on the size of the target pointer,
not the source, it was copying only 1 byte rather than the intended 8.

Spotted-by: Thomas Tuttle <ttuttle@google.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>

diff -r 5030869d9ded fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c	Thu Jun 05 04:01:40 2008 +0000
+++ b/fs/proc/task_mmu.c	Thu Jun 05 15:45:00 2008 -0500
@@ -531,7 +531,7 @@
 		return PM_END_OF_BUFFER;
 	}
 
-	if (put_user(pfn, pm->out))
+	if (put_user(pfn, (u64 *)pm->out))
 		return -EFAULT;
 	pm->out += PM_ENTRY_BYTES;
 	return 0;


-- 
Mathematics is the supreme nostalgia of our time.