Re: BUG at mm/mmap.c:2309 when cx18.ko and cx18-alsa.ko loaded
From: Andy Walls
Date: Thu Mar 10 2011 - 19:34:29 EST
On Sun, 2011-03-06 at 16:04 -0500, Andy Walls wrote:
> On Sun, 2011-03-06 at 10:37 -0800, Hugh Dickins wrote:
> > I do expect the underlying problem to be somewhere down the driver
> > end, given that nobody else has been reporting these issues. I'm
> > hoping that once the cx18 guys have time to try to reproduce it,
> > they'll be better able to track it down.
Hi Hugh,
You were correct. The mistake was in the cx18 driver, in the last thing
that I touched, of course. The code causing the bug isn't anywhere
aside from my private repo.
All,
Sorry for all the noise.
The bug was so idiotic, I fell compelled to show the fix:
diff --git a/drivers/media/video/cx18/cx18-scb.c b/drivers/media/video/cx18/cx18
index fd89ad0..d17ffc8 100644
--- a/drivers/media/video/cx18/cx18-scb.c
+++ b/drivers/media/video/cx18/cx18-scb.c
@@ -28,8 +28,8 @@
int cx18_scb_init_mdl_ent_mgmt(struct cx18 *cx)
{
- cx->scb_mdl_ent_map = kzalloc(BITS_TO_LONGS(SCB_MDL_ENTRIES),
- GFP_KERNEL);
+ cx->scb_mdl_ent_map = kzalloc(BITS_TO_LONGS(SCB_MDL_ENTRIES)
+ * sizeof(long), GFP_KERNEL);
if (cx->scb_mdl_ent_map == NULL) {
CX18_ERR("Fatal: unable to allocate bitmap for managing SCB MDL"
"entries\n");
So now the subsequent call to
bitmap_zero(cx->scb_mdl_ent_map, SCB_MDL_ENTRIES);
doesn't walk off the end of what was allocated.
Apparently BITS_TO_LONGS() is not BITS_TO_LONGS_TO_BYTES().
Regards,
Andy
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