if_sge related panics

[Pyun YongHyeon]

On Mon, May 24, 2010 at 09:48:33AM -0400, John Baldwin wrote:
> On Monday 24 May 2010 6:35:01 am Nikolay Denev wrote:
> > On May 24, 2010, at 8:57 AM, Nikolay Denev wrote:
> > 
> > > Hi,
> > > 
> > > Recently I started to experience a if_sge(4) related panic.
> > > It happens almost every time I try to download a torrent file for example.
> > > Copying of large files over NFS seem not to trigger it, but I haven't tested extensively.
> > > 
> > > Here is the panic message :
> > > 
> > > Fatal trap 12: page fault while in kernel mode
> > > cpuid = 0; apic id = 00
> > > fault virtual address		= 0x8
> > > fault code				= supervisor write data, page not present
> > > instruction pointer		= 0x20:0xffffffff80230413
> > > stack pointer				= 0x28:0xffffff80001e9280
> > > frame pointer			= 0x28:0xffffff80001e9510
> > > code segment			= base 0x0, limit 0xfffff, type 0x1b
> > > 						= DPL 0, pres 1, long 1, def32 0, gran 1
> > > processor eflags			= interrupt enabled, resume, IOPL = 0
> > > current process			= 12 (irq19: sge0)
> > > trap number				= 12
> > > panic: page fault
> > > cpuid = 0
> > > Uptime: 1d20h56m20s
> > > Cannot dump. Device not defined or unavailable
> > > Automatic reboot in 15 seconds - press a key on the console to abort
> > > Sleeping thread (tid 100039, pid 12) owns a non-sleepable lock
> > > 
> > > My swap is on a zvol, so I don't have dump. I'll try to attach a disk on the eSATA port and dump there if needed.
> > 
> > Here is some info from the crashdump :
> > 
> > (kgdb) #0  doadump () at pcpu.h:223
> > #1  0xffffffff802fb149 in boot (howto=260)
> >     at /usr/src/sys/kern/kern_shutdown.c:416
> > #2  0xffffffff802fb57c in panic (fmt=0xffffffff8055d564 "%s")
> >     at /usr/src/sys/kern/kern_shutdown.c:590
> > #3  0xffffffff805055b8 in trap_fatal (frame=0xffffff000288a3e0, eva=Variable "eva" is not available.
> > )
> >     at /usr/src/sys/amd64/amd64/trap.c:777
> > #4  0xffffffff805059dc in trap_pfault (frame=0xffffff80001e91d0, usermode=0)
> >     at /usr/src/sys/amd64/amd64/trap.c:693
> > #5  0xffffffff805061c5 in trap (frame=0xffffff80001e91d0)
> >     at /usr/src/sys/amd64/amd64/trap.c:451
> > #6  0xffffffff804eb977 in calltrap ()
> >     at /usr/src/sys/amd64/amd64/exception.S:223
> > #7  0xffffffff80230413 in sge_start_locked (ifp=0xffffff000270d800)
> >     at /usr/src/sys/dev/sge/if_sge.c:1591
> 
> Try this.  sge_encap() can sometimes return an error with m_head set to NULL:
> 

Thanks John. Committed in r208512.

> Index: if_sge.c
> ===================================================================
> --- if_sge.c	(revision 208375)
> +++ if_sge.c	(working copy)
> @@ -1588,7 +1588,8 @@
>  		if (m_head == NULL)
>  			break;
>  		if (sge_encap(sc, &m_head)) {
> -			IFQ_DRV_PREPEND(&ifp->if_snd, m_head);
> +			if (m_head != NULL)
> +				IFQ_DRV_PREPEND(&ifp->if_snd, m_head);
>  			ifp->if_drv_flags |= IFF_DRV_OACTIVE;
>  			break;
>  		}
> 
> -- 
> John Baldwin