What does "net_ratelimit: 44 callbacks suppressed" mean on a linux?

Solution 1:

'net_ratelimit()' is used to limit syslog messages from kernel.
This "callbacks suppressed" message implies it suppressed a bulk of 44 syslog messages.
This is an attempt to avoid loading your syslog logging path.

Here is the source reference if you are interested,
FreeBSD/Linux Kernel Cross Reference; sys/net/core/utils.c,
It calls sys/lib/ratelimit.c -- ___ratelimit()

You might want to investigate your "martian source",
but if you ignore it I guess, the ratelimit will handle the logs
(it is usually a good idea to fix unknown log sources tho).

In your case it appears like your Martian Packets are,

An incoming or outgoing packet whose source or destination address is in the range 127.0.0.0/8, which is reserved for loopback within the host.