On Sat, Dec 27, 2014 at 02:17:37PM -0600, Larry Finger wrote:

These drivers use 9100-byte receive buffers, thus allocating an skb requires
an O(3) memory allocation. Under heavy memory loads and fragmentation, such
a request can fail. Previous versions of the driver have dropped the packet
and reused the old buffer; however, the new version introduced a bug in that
it released the old buffer before trying to allocate a new one. The previous
method is implemented here.

It looks like in the out-of-memory path, pci_map_single() gets called while the
skb is still mapped.  Won't this leak the IOMMU mapping?