Re: v4.14-rc3/arm64 DABT exception in atomic_inc() / __skb_clone()

On Wed, Oct 25, 2017 at 11:49 AM, Willem de Bruijn
[off-list ref] wrote:

From skb->dev and netdev_priv, the tun device has flags 0x1002 ==
IFF_TAP | IFF_NO_PI. This kernel precedes the recent support for
IFF_NAPI and IFF_NAPI_FRAGS. The allocation most likely happened
in tun_build_skb from current->task_frag. It would be a previous
allocation that left alloc_frag->offset unaligned. But perhaps this code
needs to perform alignment before setting skb->head. At least on
platforms where atomic on dataref must be aligned.

+1

Bug added in commit 66ccbc9c87c2 ("tap: use build_skb() for small packet")