Messages in this thread Patch in this message | | | Date | Mon, 19 Nov 2007 15:22:52 -0800 | From | Greg KH <> | Subject | Re: [stable] Soft lockups since stable kernel upgrade to 2.6.23.8 |
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On Sat, Nov 17, 2007 at 04:34:56PM -0800, Jeremy Fitzhardinge wrote: > Greg KH wrote: > > Great, thanks for tracking this down. > > > > Ingo, this corrisponds to changeset > > a115d5caca1a2905ba7a32b408a6042b20179aaa in mainline. Is that patch > > incorrect? Should this patch in the -stable tree be reverted? > > > > Hm, I've never observed a problem with this in mainline. > > Ah. The significant difference between 2.6.23 and -git is that the > former used sched_clock as the softlockup timebase, versus cpu_clock in > git. If sched_clock() is tsc-based, and the tsc isn't stable when using > cpufreq, then the softlockup with get confused and fire spuriously. > Ingo's fix to reporting exposed the fact that softlockup is terminally > broken in that kernel. > > I think the best course for now is to revert it, since softlockup is > hardly a critical feature. The proper fixes would either be to backport > cpu_clock() to 2.6.23, or make it go back to using ticks.
Can you try applying the patch below to see if that solves the problem for you?
thanks,
greg k-h
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From: Ingo Molnar <mingo@elte.hu> Date: Sun, 18 Nov 2007 01:55:38 +0100 Subject: softlockup watchdog fixes and cleanups To: Greg KH <greg@kroah.com> Cc: David <david@unsolicited.net>, Jeremy Fitzhardinge <jeremy@goop.org>, gregkh@suse.de, Javier Kohen <jkohen@users.sourceforge.net>, Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, stable@kernel.org Message-ID: <20071118005538.GD26865@elte.hu> Content-Disposition: inline
From: Ingo Molnar <mingo@elte.hu>
This is a merge of commits a5f2ce3c6024a5bb895647b6bd88ecae5001020a and 43581a10075492445f65234384210492ff333eba in mainline to fix a warning in the 2.6.23.3 kernel release.
softlockup watchdog: style cleanups
kernel/softirq.c grew a few style uncleanlinesses in the past few months, clean that up. No functional changes:
text data bss dec hex filename 1126 76 4 1206 4b6 softlockup.o.before 1129 76 4 1209 4b9 softlockup.o.after
( the 3 bytes .text increase is due to the "<1>" appended to one of the printk messages. )
Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
softlockup: improve debug output
Improve the debuggability of kernel lockups by enhancing the debug output of the softlockup detector: print the task that causes the lockup and try to print a more intelligent backtrace.
The old format was:
BUG: soft lockup detected on CPU#1! [<c0105e4a>] show_trace_log_lvl+0x19/0x2e [<c0105f43>] show_trace+0x12/0x14 [<c0105f59>] dump_stack+0x14/0x16 [<c015f6bc>] softlockup_tick+0xbe/0xd0 [<c013457d>] run_local_timers+0x12/0x14 [<c01346b8>] update_process_times+0x3e/0x63 [<c0145fb8>] tick_sched_timer+0x7c/0xc0 [<c0140a75>] hrtimer_interrupt+0x135/0x1ba [<c011bde7>] smp_apic_timer_interrupt+0x6e/0x80 [<c0105aa3>] apic_timer_interrupt+0x33/0x38 [<c0104f8a>] syscall_call+0x7/0xb =======================
The new format is:
BUG: soft lockup detected on CPU#1! [prctl:2363]
Pid: 2363, comm: prctl EIP: 0060:[<c013915f>] CPU: 1 EIP is at sys_prctl+0x24/0x18c EFLAGS: 00000213 Not tainted (2.6.22-cfs-v20 #26) EAX: 00000001 EBX: 000003e7 ECX: 00000001 EDX: f6df0000 ESI: 000003e7 EDI: 000003e7 EBP: f6df0fb0 DS: 007b ES: 007b FS: 00d8 CR0: 8005003b CR2: 4d8c3340 CR3: 3731d000 CR4: 000006d0 [<c0105e4a>] show_trace_log_lvl+0x19/0x2e [<c0105f43>] show_trace+0x12/0x14 [<c01040be>] show_regs+0x1ab/0x1b3 [<c015f807>] softlockup_tick+0xef/0x108 [<c013457d>] run_local_timers+0x12/0x14 [<c01346b8>] update_process_times+0x3e/0x63 [<c0145fcc>] tick_sched_timer+0x7c/0xc0 [<c0140a89>] hrtimer_interrupt+0x135/0x1ba [<c011bde7>] smp_apic_timer_interrupt+0x6e/0x80 [<c0105aa3>] apic_timer_interrupt+0x33/0x38 [<c0104f8a>] syscall_call+0x7/0xb =======================
Note that in the old format we only knew that some system call locked up, we didnt know _which_. With the new format we know that it's at a specific place in sys_prctl(). [which was where i created an artificial kernel lockup to test the new format.]
This is also useful if the lockup happens in user-space - the user-space EIP (and other registers) will be printed too. (such a lockup would either suggest that the task was running at SCHED_FIFO:99 and looping for more than 10 seconds, or that the softlockup detector has a false-positive.)
The task name is printed too first, just in case we dont manage to print a useful backtrace.
[satyam@infradead.org: fix warning] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Satyam Sharma <satyam@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/softlockup.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-)
--- a/kernel/softlockup.c +++ b/kernel/softlockup.c @@ -15,13 +15,16 @@ #include <linux/notifier.h> #include <linux/module.h> +#include <asm/irq_regs.h> + static DEFINE_SPINLOCK(print_lock); static DEFINE_PER_CPU(unsigned long, touch_timestamp); static DEFINE_PER_CPU(unsigned long, print_timestamp); static DEFINE_PER_CPU(struct task_struct *, watchdog_task); -static int did_panic = 0; +static int did_panic; +int softlockup_thresh = 10; static int softlock_panic(struct notifier_block *this, unsigned long event, void *ptr) @@ -70,6 +73,7 @@ void softlockup_tick(void) int this_cpu = smp_processor_id(); unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu); unsigned long print_timestamp; + struct pt_regs *regs = get_irq_regs(); unsigned long now; if (touch_timestamp == 0) { @@ -99,21 +103,26 @@ void softlockup_tick(void) wake_up_process(per_cpu(watchdog_task, this_cpu)); /* Warn about unreasonable 10+ seconds delays: */ - if (now > (touch_timestamp + 10)) { - per_cpu(print_timestamp, this_cpu) = touch_timestamp; + if (now <= (touch_timestamp + softlockup_thresh)) + return; + + per_cpu(print_timestamp, this_cpu) = touch_timestamp; - spin_lock(&print_lock); - printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n", - this_cpu); + spin_lock(&print_lock); + printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n", + this_cpu, now - touch_timestamp, + current->comm, current->pid); + if (regs) + show_regs(regs); + else dump_stack(); - spin_unlock(&print_lock); - } + spin_unlock(&print_lock); } /* * The watchdog thread - runs every second and touches the timestamp. */ -static int watchdog(void * __bind_cpu) +static int watchdog(void *__bind_cpu) { struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; @@ -151,13 +160,13 @@ cpu_callback(struct notifier_block *nfb, BUG_ON(per_cpu(watchdog_task, hotcpu)); p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu); if (IS_ERR(p)) { - printk("watchdog for %i failed\n", hotcpu); + printk(KERN_ERR "watchdog for %i failed\n", hotcpu); return NOTIFY_BAD; } - per_cpu(touch_timestamp, hotcpu) = 0; - per_cpu(watchdog_task, hotcpu) = p; + per_cpu(touch_timestamp, hotcpu) = 0; + per_cpu(watchdog_task, hotcpu) = p; kthread_bind(p, hotcpu); - break; + break; case CPU_ONLINE: case CPU_ONLINE_FROZEN: wake_up_process(per_cpu(watchdog_task, hotcpu)); @@ -177,7 +186,7 @@ cpu_callback(struct notifier_block *nfb, kthread_stop(p); break; #endif /* CONFIG_HOTPLUG_CPU */ - } + } return NOTIFY_OK; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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