[Qemu-devel] memory leak in user mode network stack

[Juergen Keil]

Hi,

apparently there is a qemu memory leak when -user-net is used.  ftp'ing a
~500Mbyte file from the host os to the guest os increases memory usage for
the "qemu -m 256" process from ~280mb to almost 2gb.

It seems the problem is in slirp/if.c, if_start().  If fetches queued mbuf's,
sends them, but does not return the mbufs to the free mbuf pool.


Shouldn't if_start() return mbufs to the free mbuf pool after transmitting
the data, like this?

Index: if.c
===================================================================
RCS file: /cvsroot/qemu/qemu/slirp/if.c,v
retrieving revision 1.1
diff -u -B -c -8 -r1.1 if.c
cvs diff: conflicting specifications of output style
*** if.c        22 Apr 2004 00:10:47 -0000      1.1
--- if.c        13 Sep 2004 16:29:32 -0000
***************
*** 310,320 ****
--- 310,322 ----
                if (--ifm->ifq_so->so_queued == 0)
                   /* If there's no more queued, reset nqueued */
                   ifm->ifq_so->so_nqueued = 0;
        }
  
        /* Encapsulate the packet for sending */
          if_encap(ifm->m_data, ifm->m_len);
  
+       m_free(ifm);
+ 
        if (if_queued)
           goto again;
  }