From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1JpU5M-0008Sw-2Q for user-mode-linux-devel@lists.sourceforge.net; Fri, 25 Apr 2008 12:59:56 -0700 Received: from 41-052.adsl.zetnet.co.uk ([194.247.41.52] helo=mail.esperi.org.uk) by mail.sourceforge.net with esmtp (Exim 4.44) id 1JpU5K-0000RS-1b for user-mode-linux-devel@lists.sourceforge.net; Fri, 25 Apr 2008 12:59:55 -0700 From: Nix Date: Fri, 25 Apr 2008 20:59:38 +0100 Message-ID: <877iel7ljp.fsf@hades.wkstn.nix> MIME-Version: 1.0 Subject: [uml-devel] actually useful backtrace from a CPU-chewing hang List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: Jeff Dike Cc: user-mode-linux-devel@lists.sourceforge.net I suspect this can go wrong anywhere, but it happens to have been a CBQ-triggered gettimeofday() while sending an arp that did it. (My ADSL router pretty much bombs the poor damn machine with ARP packets all the time.) #0 getnstimeofday (ts=3D0x8217d10) at include/linux/time.h:182 #1 0x080824b4 in ktime_get_ts (ts=3D0x8217d10) at kernel/hrtimer.c:122 #2 0x0808244b in ktime_get () at kernel/hrtimer.c:58 #3 0x08148d93 in cbq_dequeue (sch=3D0xdde3800) at include/net/pkt_sched.h:= 53 #4 0x08143355 in __qdisc_run (dev=3D0xded1800) at net/sched/sch_generic.c:= 85 #5 0x08137991 in dev_queue_xmit (skb=3D0xdc89380) at include/net/pkt_sched= .h:89 #6 0x08185537 in arp_xmit (skb=3D0xdc89380) at net/ipv4/arp.c:668 #7 0x08185574 in arp_send (type=3D1, ptype=3D2054, dest_ip=3D3457507285, d= ev=3D0xded1800, src_ip=3D2668538048, dest_hw=3D0xdd65244 "", src_hw=3D0xded= 192c "\002`\227y=E2=C1", target_hw=3D0x0) at net/ipv4/arp.c:694 #8 0x08184fb2 in arp_solicit (neigh=3D0xdd65220, skb=3D0x0) at net/ipv4/ar= p.c:379 #9 0x0813c898 in neigh_timer_handler (arg=3D232149536) at net/core/neighbo= ur.c:866 #10 0x08077afd in run_timer_softirq (h=3D0x823a3ec) at kernel/timer.c:664 #11 0x080740a4 in __do_softirq () at kernel/softirq.c:234 #12 0x0807412e in do_softirq () at kernel/softirq.c:271 #13 0x08074186 in irq_exit () at kernel/softirq.c:310 #14 0x080576fd in do_IRQ (irq=3D0, regs=3D0x8217ec4) at arch/um/kernel/irq.= c:336 #15 0x080590a0 in timer_handler (sig=3D26, regs=3D0x8217ec4) at arch/um/ker= nel/time.c:28 #16 0x08064c84 in real_alarm_handler (sc=3D0x0) at arch/um/os-Linux/signal.= c:93 #17 0x08064cac in alarm_handler (sig=3D26, sc=3D0x0) at arch/um/os-Linux/si= gnal.c:108 #18 0x080654a0 in deliver_alarm () at arch/um/os-Linux/time.c:117 #19 0x08065640 in idle_sleep (nsecs=3D) at arch/um/os-= Linux/time.c:181 #20 0x080580d4 in default_idle () at arch/um/kernel/process.c:248 #21 0x080580fe in cpu_idle () at arch/um/kernel/process.c:256 #22 0x081afdee in rest_init () at init/main.c:453 #23 0x0804953b in start_kernel () at init/main.c:650 #24 0x0804a7e1 in start_kernel_proc (unused=3D0x0) at arch/um/kernel/skas/p= rocess.c:46 #25 0x08064261 in run_kernel_thread (fn=3D0x804a7b5 , ar= g=3D0x0, jmp_ptr=3D0x821d184) at arch/um/os-Linux/process.c:267 #26 0x08057ee0 in new_thread_handler () at arch/um/kernel/process.c:151 #27 0x00000000 in ?? () (gdb) frame 1 #1 0x080824b4 in ktime_get_ts (ts=3D0x8217d10) at kernel/hrtimer.c:122 122 getnstimeofday(ts); (gdb) print *ts $3 =3D {tv_sec =3D -1963377075, tv_nsec =3D 320917000} It's stuck inside timespec_add_ns(), never leaving: this has been inlined, so spying on its locals or parameters with GDB is pretty much a no-hoper :/ Still, it's obvious enough to me that __get_nsec_offset() is returning a negative value in getnstimeofday(), so timespec_add_ns() is looping, well, not *forever*, but near enough, trying to push that u64 back down to zero in units of NSEC_PER_SEC... I hope this gives you a bit more of a clue. ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference = Don't miss this year's exciting event. There's still time to save $100. = Use priority code J8TL2D2. = http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/java= one _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel