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

[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;
  }

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

[Darryl Dixon]

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I can verify this behaviour; I have a bug filed on the savannah site.


D


On Tue, 2004-09-14 at 04:46, Juergen Keil wrote:

> 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;
>   }
> 
> 
> 
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel

-- 
Darryl Dixon <esrever_otua@pythonhacker.is-a-geek.net>

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