Ingo Molnar wrote:

Then i tried both suggested fix patches Patrick sent me (a suggested 
revert and an netfilter/RCU use-after-free fix), but none of them solved 
the crash.

Just to make sure - the "netfilter/RCU use-after-free fix" was the
patch from Pekka?

Thus i finally arrived to:

 # good: [ae6134bd] hdlcdrv: Fix CRC calculation.
 # bad:  [5547cd0d] netfilter: nf_conntrack_sctp: fix sparse warnings
 # bad:  [280763c6] netfilter: xt_time: fix time's time_mt()'s use of
 # good: [07a7c10b] netlink: add NLA_PUT_BE64 macro
 # bad:  [58401573] netfilter: accounting rework: ct_extend + 64bit co

| 584015727a3b88b46602b20077b46cd04f8b4ab3 is first bad commit
| commit 584015727a3b88b46602b20077b46cd04f8b4ab3
| Author: Krzysztof Piotr Oledzki [off-list ref]
| AuthorDate: Mon Jul 21 10:01:34 2008 -0700
| Commit:     David S. Miller [off-list ref]
| CommitDate: Mon Jul 21 10:10:58 2008 -0700
|
|    netfilter: accounting rework: ct_extend + 64bit counters (v4)
[...]
|     Signed-off-by: Krzysztof Piotr Oledzki [off-list ref]
|     Signed-off-by: Patrick McHardy [off-list ref]
|     Signed-off-by: David S. Miller [off-list ref]

Which i double-checked by reverting that commit from -git as well and 
that solved the crash. Find the tested reverter patch below.

Thats odd. I don't think anything is wrong with that patch
itself, its more likely that its triggering a bug in
ct_extend. You config has a few helper enabled (FTP, H.323,
TFTP) and the crash is when trying to call the helper functions.
Did you actually have traffic of one of these protocols?