From: Dave Boutcher <boutcher@cs.umn.edu>

Earlier code relied on a broken length calculation copy /proc/pid/pagemap
header data to userspace.  This fix correctly calls the add_to_pagemap
routine after the header data is set to copy results to userspace in a sane
fashion.

Signed-off-by: Dave Boutcher <boutcher@cs.umn.edu>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/task_mmu.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -puN fs/proc/task_mmu.c~maps2-add-proc-pid-pagemap-interface-fix-proc-pid-pagemap-header-copy-to-userspace fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~maps2-add-proc-pid-pagemap-interface-fix-proc-pid-pagemap-header-copy-to-userspace
+++ a/fs/proc/task_mmu.c
@@ -689,11 +689,11 @@ static ssize_t pagemap_read(struct file 
 	pm.out = buf;
 
 	if (svpfn == -1) {
-		add_to_pagemap(pm.next, 0, &pm);
 		((char *)page)[0] = (ntohl(1) != 1);
 		((char *)page)[1] = PAGE_SHIFT;
 		((char *)page)[2] = sizeof(unsigned long);
 		((char *)page)[3] = sizeof(unsigned long);
+		add_to_pagemap(pm.next, page[0], &pm);
 	}
 
 	down_read(&mm->mmap_sem);
_