Re: [dm-devel] Re: 2.6.28.2 & dm-snapshot or kcopyd Oops

[Mikulas Patocka <mpatocka redhat com>]

On Fri, 13 Feb 2009, Jacky Kim wrote:

> Hi,
> 
> 1. I test with the origin LV, and don't write to snapshots.
> 2. I don't delete snapshots when copy big files to the origin LV, but do create snapshot sometimes.
> 3. The snapshots have the same chunk size: 4KB or 64KB.
> 4. It seems to work well with 1 snapshot. But it always crashes each time with 2 snapshots.
> 5. I don't resize the origin device and the snapshots.
> 
> The latest debug information is as follows:

Ohhh, the last patch from me was wrong, so it could produce a false 
positive, so its result is unusable. Apply this on the top of it.

Mikulas

---
 drivers/md/dm-snap.c |    1 +
 1 file changed, 1 insertion(+)

Index: linux-2.6.28-snap-debug/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.28-snap-debug.orig/drivers/md/dm-snap.c	2009-02-16 08:09:22.000000000 +0100
+++ linux-2.6.28-snap-debug/drivers/md/dm-snap.c	2009-02-16 08:09:47.000000000 +0100
@@ -874,6 +874,7 @@ static struct bio *put_pending_exception
 	pe->snap->store.check_pending_exception(&pe->snap->store, pe, __LINE__);
 
 	primary_pe = pe->primary_pe;
+	pe->primary_pe = NULL;
 
 	if (primary_pe) {
 		if (atomic_read(&primary_pe->ref_count) <= 0 || primary_pe->magic != 0x12345678) {