On Mon, 23 Apr 2007 23:58:20 -0700 Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote: > Andrew Morton wrote: > > On Tue, 27 Mar 2007 14:49:20 -0700 Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote: > > > > > >> The softlockup watchdog is currently a nuisance in a virtual machine, > >> since the whole system could have the CPU stolen from it for a long > >> period of time. While it would be unlikely for a guest domain to be > >> denied timer interrupts for over 10s, it could happen and any softlockup > >> message would be completely spurious. > >> > >> Earlier I proposed that sched_clock() return time in unstolen > >> nanoseconds, which is how Xen and VMI currently implement it. If the > >> softlockup watchdog uses sched_clock() to measure time, it would > >> automatically ignore stolen time, and therefore only report when the > >> guest itself locked up. When running native, sched_clock() returns > >> real-time nanoseconds, so the behaviour would be unchanged. > >> > >> Note that sched_clock() used this way is inherently per-cpu, so this > >> patch makes sure that the per-processor watchdog thread initialized > >> its own timestamp. > >> > > > > This patch > > (ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21-rc6/2.6.21-rc6-mm1/broken-out/ignore-stolen-time-in-the-softlockup-watchdog.patch) > > causes six failures in the locking self-tests, which I must say is rather > > clever of it. > > > > Interesting. I'll say. > Which variation of sched_clock do you have in your tree at > the moment? Andi's, plus the below fix. Sigh. I thought I was only two more bugs away from a release, then... [18014389.347124] BUG: unable to handle kernel paging request at virtual address 6b6b7193 [18014389.347142] printing eip: [18014389.347149] c029a80c [18014389.347156] *pde = 00000000 [18014389.347166] Oops: 0000 [#1] [18014389.347174] Modules linked in: i915 drm ipw2200 sonypi ipv6 autofs4 hidp l2cap bluetooth sunrpc nf_conntrack_netbios_ns ipt_REJECT nf_conntrack_ipv4 xt_state nf_conntrack nfnetlink xt_tcpudp iptable_filter ip_tables x_tables cpufreq_ondemand video sbs button battery asus_acpi ac nvram ohci1394 ieee1394 ehci_hcd uhci_hcd sg joydev snd_hda_intel snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss snd_pcm sr_mod cdrom snd_timer ieee80211 i2c_i801 piix ieee80211_crypt i2c_core generic snd soundcore snd_page_alloc ext3 jbd ide_disk ide_core [18014389.347520] CPU: 0 [18014389.347521] EIP: 0060:[<c029a80c>] Tainted: G D VLI [18014389.347522] EFLAGS: 00010296 (2.6.21-rc7-mm1 #35) [18014389.347547] EIP is at input_release_device+0x8/0x4e [18014389.347555] eax: c99709a8 ebx: 6b6b6b6b ecx: 00000286 edx: 00000000 [18014389.347563] esi: 6b6b6b6b edi: c99709cc ebp: c21e3d40 esp: c21e3d38 [18014389.347571] ds: 007b es: 007b fs: 00d8 gs: 0000 ss: 0068 [18014389.347580] Process khubd (pid: 159, ti=c21e2000 task=c20a62f0 task.ti=c21e2000) [18014389.347588] Stack: 6b6b6b6b c99709a8 c21e3d60 c029b489 c2014ec8 c9182000 c96b167c c9970954 [18014389.347655] c9970954 c99709cc c21e3d80 c029d401 c9977a6c c96b1000 c21e3d90 c9970954 [18014389.347708] c99709a8 c9164000 c21e3d90 c029d4b5 c96b1000 c9970564 c21e3db0 c029c50b [18014389.347771] Call Trace: [18014389.347792] [<c029b489>] input_close_device+0x13/0x51 [18014389.347810] [<c029d401>] mousedev_destroy+0x29/0x7e [18014389.347827] [<c029d4b5>] mousedev_disconnect+0x5f/0x63 [18014389.347842] [<c029c50b>] input_unregister_device+0x6a/0x100 [18014389.347858] [<c02abf9c>] hidinput_disconnect+0x24/0x41 [18014389.347874] [<c02aef29>] hid_disconnect+0x79/0xc9 [18014389.347889] [<c028e1db>] usb_unbind_interface+0x47/0x8f [18014389.347916] [<c0256852>] __device_release_driver+0x74/0x90 [18014389.347933] [<c0256c5f>] device_release_driver+0x37/0x4e [18014389.347957] [<c02561c6>] bus_remove_device+0x73/0x82 [18014389.347977] [<c02547c1>] device_del+0x214/0x28c [18014389.348132] [<c028bb72>] usb_disable_device+0x62/0xc2 [18014389.348148] [<c0288893>] usb_disconnect+0x99/0x126 [18014389.348163] [<c0288d2c>] hub_thread+0x3a5/0xb07 [18014389.348178] [<c012cbe5>] kthread+0x6e/0x79 [18014389.348194] [<c0104917>] kernel_thread_helper+0x7/0x10 [18014389.348210] ======================= [18014389.348218] INFO: lockdep is turned off. [18014389.348224] Code: 5b 5d c3 55 b9 f0 ff ff ff 8b 50 0c 89 e5 83 ba 28 06 00 00 00 75 08 89 82 28 06 00 00 31 c9 5d 89 c8 c3 55 89 e5 56 53 8b 70 0c <39> 86 28 06 00 00 75 3a 8b 9e e4 08 00 00 c7 86 28 06 00 00 00 I dunno. I'll keep plugging for another couple hours then I'll shove out what I have as a -mm snapshot whatsit. Things are just ridiculous. I'm thinking of having a hard-disk crash and accidentally losing everything. From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> WARNING: arch/x86_64/kernel/built-in.o - Section mismatch: reference to .init.text:sc_cpu_event from .data between 'sc_cpu_notifier' (at offset 0x2110) and 'mcelog' Use hotcpu_notifier(). This takes care of making sure that the unused code disappears from vmlinux if !CONFIG_HOTPLUG_CPU, too. Please, test allnoconfig builds and watch for the warnings? Cc: Andi Kleen <ak@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/i386/kernel/sched-clock.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff -puN arch/i386/kernel/sched-clock.c~fix-x86_64-mm-sched-clock-share arch/i386/kernel/sched-clock.c --- a/arch/i386/kernel/sched-clock.c~fix-x86_64-mm-sched-clock-share +++ a/arch/i386/kernel/sched-clock.c @@ -169,20 +169,15 @@ sc_cpu_event(struct notifier_block *self return NOTIFY_DONE; } -static struct notifier_block sc_cpu_notifier = { - .notifier_call = sc_cpu_event -}; - static __init int init_sched_clock(void) { struct cpufreq_freqs f = { .cpu = get_cpu(), .new = 0 }; WARN_ON(num_online_cpus() > 1); call_r_s_f(&f); put_cpu(); - register_cpu_notifier(&sc_cpu_notifier); + hotcpu_notifier(sc_cpu_event, 0); cpufreq_register_notifier(&sc_freq_notifier, CPUFREQ_TRANSITION_NOTIFIER); return 0; } core_initcall(init_sched_clock); - _ _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
