Messages in this thread | | | Date | Thu, 06 Jul 2006 11:18:10 -0500 | From | "Mr. Berkley Shands" <> | Subject | 2.6.17 x86_64 regression - reboot fails due to deadlock |
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With a SuperMicro H8DC8 (nvidia chipset), Dual Opteron 285's, 16GB, Centos 4.3 -
Under 2.6.16 both the tyan 2895 and the supermicro H8DC8 both will reboot corectly, in kernel/sys.c machine_restart() gets called. But with the changes to sys.c under 2.6.17, a new path is introduced, calling void kernel_restart_prepare(char *cmd) which calls blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); (line 588) Which looks at the first element of the notifier list, and blocks forever. But ONLY on the supermicro. The tyan, a very similar motherboard does not deadlock. It returns and still calls machine_restart(). So neither reboot nor "shutdown -fh now" actually get to the bios calls.
on the supermicro, (linux-2.6.17/kernel/sys.c)
static int __kprobes notifier_call_chain(struct notifier_block **nl, unsigned long val, void *v) { int ret = NOTIFY_DONE; struct notifier_block *nb;
nb = rcu_dereference(*nl); while (nb) { ret = nb->notifier_call(nb, val, v); /* this is the deadlock for the first entry */ if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK) break; nb = rcu_dereference(nb->next); } return ret; }
I see that 2.6.18 reworks this code further.
If I want to hurt myself really, really badly, disabling the call to blocking_notifier_call_chain(&reboot_notifier_list,... restores the reboot/power off functions.
In kdb, the system sits idle awaiting something to schedule, but nothing will schedule since there is a deadlock on the supermicro. Any clues as to how to find which notifier is deadlocked?
berkley
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