From: Wu Fengguang on
From: Wu Fengguang <fengguang.wu(a)>

commit c85e9a97c4102ce2e83112da850d838cfab5ab13 upstream.

write_kmem() used to assume vwrite() always return the full buffer length.
However now vwrite() could return 0 to indicate memory hole. This creates
a bug that "buf" is not advanced accordingly.

Fix it to simply ignore the return value, hence the memory hole.

CC: Andi Kleen <andi(a)>
CC: Benjamin Herrenschmidt <benh(a)>
CC: Christoph Lameter <cl(a)>
CC: Ingo Molnar <mingo(a)>
CC: Tejun Heo <tj(a)>
CC: Nick Piggin <npiggin(a)>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)>
CC: <stable(a)>
Signed-off-by: Wu Fengguang <fengguang.wu(a)>
drivers/char/mem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.32.orig/drivers/char/mem.c 2010-02-04 10:37:55.000000000 +0800
+++ linux-2.6.32/drivers/char/mem.c 2010-02-04 10:37:59.000000000 +0800
@@ -599,7 +599,7 @@ static ssize_t write_kmem(struct file *
- len = vwrite(kbuf, (char *)p, len);
+ vwrite(kbuf, (char *)p, len);
count -= len;
buf += len;
virtr += len;
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