Bug#878242: linux-image-4.12.0-2-marvell: flood of messages "mv643xx_eth_port mv643xx_eth_port.0 eth0: failed to linearize skb with tiny unaligned fragment"
Hi, Ben.
On Oct 11 2017, Ben Hutchings wrote:
> On Wed, 2017-10-11 at 11:48 -0300, rbrito@ime.usp.br wrote:
> > I am using an armel system with only 128MB of RAM (a KuroBox Pro) running
> > Debian testing and, if my memory serves me well, I started seeing lots and
> > lots of messages like:
> >
> > mv643xx_eth_port mv643xx_eth_port.0 eth0: failed to linearize skb with tiny unaligned fragment
> >
> > on my dmesg after I upgraded to kernel 4.12. I don't know if this is a
> > serious problem or only a cosmetic issue.
> [...]
>
> This message and the code that generates it have been present in the
> mv643xx_eth driver for a long time. The network interface hardware is
> generally capable of transmitting a packet that comes from multiple
> buffers in memory, but in some cases the driver copies all the data
> into a single buffer, probably to avoid a hardware bug. If there is
> not enough memory to make that copy then it logs this message.
Oh, thanks for the explanation.
> I think the driver should drop the packet if this happens, but instead
> it just reports that the hardware is busy. That will cause the kernel
> to try sending the packet again repeatedly, resulting in repetition of
> this log message until there is more memory available.
Hummm, that may be related to some lower performance that I have felt (but
not measured).
I see. Discarding the packet would flag congestion with TCP, if I understand
it correctly.
> If you haven't seen this error message before, it might be triggered by an
> application change. But I think it's more likely to be caused by higher
> memory usage or fragmentation of memory.
Yes, I think that the problem is that the programs are getting bigger and
bigger. Would setting vm.min_free_kbytes to a higher value worth it?
Anyway, I just upgraded to kernel 4.13 and I will report what I see.
Thanks,
--
Rogério Brito : rbrito@{ime.usp.br,gmail.com} : GPG key 4096R/BCFCAAAA
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