help linux timers

Good morning, in my kernel code, which handles timeouts for connection
tables in a linked list, i do:

inline void update_timer_of_state_entry(struct state_table *sttable)
{
if (sttable->state.state == ESTABLISHED)
mod_timer(&sttable->timer_statelist,
jiffies + HZ * state_lifetime);
else
mod_timer(&sttable->timer_statelist,
jiffies + HZ * setup_shutd_state_lifetime);
}

sttable is a structure which contains a struct timer_list.

In:

mod_timer(&sttable->timer_statelist,
jiffies + HZ * state_lifetime);

i update the timeout for the structures, so that when timer expires,
structure is removed from linked list.

The problem is that when state lifetime is long, let's say 2592000 for
instance, kernel goes in panic!

If the value is low, say 300, or higher 259200000, ok!

I suspect a problem of overflow .. is it possible?

What can be wrong?

Thanks a lot for any hint!

Giacomo.