if_sge related panics

John Baldwin jhb at freebsd.org
Mon May 24 13:48:59 UTC 2010


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:

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


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