panic: sf_buf_free: freeing free sf_buf

[Matthew Dillon]

:sf_buf_free(c039b5c0,c03f59e8,f33f1700,d73cccc4,c01e2090) at
:sf_buf_free+0x18
:sf_buf_mfree(f7c469c0,f33f1700,c03f59e8,da55b9c0,d73cccd8) at
:sf_buf_mfree+0x7d
:m_free(f33f1700,17,ed4a79d4,d73ccd14,c0180c57) at m_free+0x1e8
:m_freem(f6e0f000,fa83a4,da678000,15,18) at m_freem+0x2a
:em_txeof(c03f59e8,da55b9c0,d38800d0,d73ccd54,c01abad8) at em_txeof+0x14e
:em_poll(da55b9c0,0,5,0,5) at em_poll+0xe3
:netisr_poll(d388035c) at netisr_poll+0x1e4
:netmsg_service(d388035c,1,0,ff8083a4,ff808000) at netmsg_service+0x32
:netmsg_service_loop(c03f67a8,0,0,0,0) at netmsg_service_loop+0x18
:lwkt_exit() at lwkt_exit
:boot() called on cpu#1
:Uptime: 1d2h5m12s

    Side note:  For m_free() to be calling sf_buf_free() implies this
    is the sendfile() code.

						-Matt