BUG: soft lockup - CPU#3 stuck for 61s! , while running cpu controller latency testcase on two containers parallaly

Hi,

I am hitting this soft lock issue while running this scenario on 2.6.31-rc7 kernel on SystemX 32 bit on multiple machines.

Opened bug : http://bugzilla.kernel.org/show_bug.cgi?id=14150

Scenario:
- While running cpu controller latency testcase from LTP same time
on two containers.

Steps:
1. Create two container e.g:
lxc-execute -n foo1 -f /usr/etc/lxc/lxc-macvlan.conf /bin/bash
lxc-execute -n foo2 -f /usr/etc/lxc/lxc-macvlan.conf /bin/bash
2. Compile ltp-full-20090731.tgz on host.
3. Either you run cpu_latency testcase alone or run "./runltp -f controllers" at same time on both the containers.
4. After testcase execution completes, you can see this message in dmesg.

Expected Result:
- Should not reproduce soft lock up issue.
- This reproduces 3 times out of 5 tries.

hrtimer: interrupt too slow, forcing clock min delta to 5843235 ns
hrtimer: interrupt too slow, forcing clock min delta to 5842476 ns Clocksource tsc unstable (delta = 18749057581 ns)

BUG: soft lockup - CPU#3 stuck for 61s! [cpuctl_latency_:17174]
Modules linked in: bridge stp llc bnep sco l2cap bluetooth sunrpc ipv6 p4_clockmod dm_multipath uinput qla2xxx ata_generic pata_acpi usb_storage e1000 scsi_transport_fc joydev scsi_tgt i2c_piix4 pata_serverworks pcspkr serio_raw mptspi mptscsih mptbase scsi_transport_spi radeon ttm drm i2c_algo_bit i2c_core [last unloaded: scsi_wait_scan]

Pid: 17174, comm: cpuctl_latency_ Tainted: G W (2.6.31-rc7 #1) IBM eServer BladeCenter HS40 -[883961X]- EIP: 0060:[<c058aded>] EFLAGS: 00000283 CPU: 3
EIP is at find_next_bit+0x9/0x79
EAX: c2c437a0 EBX: f3d433c0 ECX: 00000000 EDX: 00000020
ESI: c2c436bc EDI: 00000000 EBP: f063be6c ESP: f063be64
DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
CR0: 80050033 CR2: 008765a4 CR3: 314d7000 CR4: 000006d0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff0ff0 DR7: 00000400

Call Trace:
[<c0427b6e>] cpumask_next+0x17/0x19
[<c042c28d>] tg_shares_up+0x53/0x149
[<c0424082>] ? tg_nop+0x0/0xc
[<c0424082>] ? tg_nop+0x0/0xc
[<c042406e>] walk_tg_tree+0x63/0x77
[<c042c23a>] ? tg_shares_up+0x0/0x149
[<c042e836>] update_shares+0x5d/0x65
[<c0432af3>] rebalance_domains+0x114/0x460
[<c0403393>] ? restore_all_notrace+0x0/0x18
[<c0432e75>] run_rebalance_domains+0x36/0xa3
[<c043c324>] __do_softirq+0xbc/0x173
[<c043c416>] do_softirq+0x3b/0x5f
[<c043c52d>] irq_exit+0x3a/0x68
[<c0417846>] smp_apic_timer_interrupt+0x6d/0x7b
[<c0403c9b>] apic_timer_interrupt+0x2f/0x34
BUG: soft lockup - CPU#2 stuck for 61s! [watchdog/2:11]
Modules linked in: bridge stp llc bnep sco l2cap bluetooth sunrpc ipv6 p4_clockmod dm_multipath uinput qla2xxx ata_generic pata_acpi usb_storage e1000 scsi_transport_fc joydev scsi_tgt i2c_piix4 pata_serverworks pcspkr serio_raw mptspi mptscsih mptbase scsi_transport_spi radeon ttm drm i2c_algo_bit i2c_core [last unloaded: scsi_wait_scan]

Pid: 11, comm: watchdog/2 Tainted: G W (2.6.31-rc7 #1) IBM eServer BladeCenter HS40 -[883961X]- EIP: 0060:[<c042c313>] EFLAGS: 00000246 CPU: 2
EIP is at tg_shares_up+0xd9/0x149
EAX: 00000000 EBX: f09b3c00 ECX: f0baac00 EDX: 00000100
ESI: 00000002 EDI: 00000400 EBP: f6cb7de0 ESP: f6cb7db8
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
CR0: 8005003b CR2: 08070680 CR3: 009c8000 CR4: 000006d0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff0ff0 DR7: 00000400

Call Trace:
[<c0424082>] ? tg_nop+0x0/0xc
[<c0424082>] ? tg_nop+0x0/0xc
[<c042406e>] walk_tg_tree+0x63/0x77
[<c042c23a>] ? tg_shares_up+0x0/0x149
[<c042e836>] update_shares+0x5d/0x65
[<c0432af3>] rebalance_domains+0x114/0x460
[<c0432e75>] run_rebalance_domains+0x36/0xa3
[<c043c324>] __do_softirq+0xbc/0x173
[<c043c416>] do_softirq+0x3b/0x5f
[<c043c52d>] irq_exit+0x3a/0x68
[<c0417846>] smp_apic_timer_interrupt+0x6d/0x7b
[<c0403c9b>] apic_timer_interrupt+0x2f/0x34
[<c0430d37>] ? finish_task_switch+0x5d/0xc4
[<c0744b11>] schedule+0x74c/0x7b2
[<c0590e28>] ? trace_hardirqs_on_thunk+0xc/0x10
[<c0403393>] ? restore_all_notrace+0x0/0x18
[<c0471e19>] ? watchdog+0x0/0x79
[<c0471e19>] ? watchdog+0x0/0x79
[<c0471e63>] watchdog+0x4a/0x79
[<c0449a53>] kthread+0x70/0x75
[<c04499e3>] ? kthread+0x0/0x75
[<c0403e93>] kernel_thread_helper+0x7/0x10

[root@hs40 ltp-full-20090731]# uname -a
Linux hs40.in.ibm.com 2.6.31-rc7 #1 SMP Thu Sep 3 10:14:41 IST 2009 i686 i686 i386 GNU/Linux [root@hs40 ltp-full-20090731]#

[Adding the scheduler maintainers to the cc]

thanks,

regards,
Dhaval

The same problem was observed while testing with 2.6.29 kernel, this is what I could gather from looking into the error message,

EIP matches to 'tg_shares_up+0xd9/0x149',
-----------------------
This maps to address location 5c37 in the objdump
/root/rpmbuild/BUILD/kernel-2.6.29/linux-2.6.29.i686/kernel/sched.c:1511

if (abs(shares - tg->se[cpu]->load.weight) >
5c33: 89 d0 mov %edx,%eax
5c35: 2b 01 sub (%ecx),%eax
5c37: 89 c1 mov %eax,%ecx
5c39: c1 f9 1f sar $0x1f,%ecx
5c3c: 31 c8 xor %ecx,%eax
5c3e: 29 c8 sub %ecx,%eax
5c40: 3b 05 00 00 00 00 cmp 0x0,%eax
5c46: 76 3d jbe 5c85 <tg_shares_up+0x127>
/root/rpmbuild/BUILD/kernel-2.6.29/linux-2.6.29.i686/kernel/sched.c:1516

                        sysctl_sched_shares_thresh) {
                struct rq *rq = cpu_rq(cpu);

-----------------------
This matches to line 1511 - 1516 in the kernel code

1511 if (abs(shares - tg->se[cpu]->load.weight) >
1512 sysctl_sched_shares_thresh) {
1513 struct rq *rq = cpu_rq(cpu);
1514 unsigned long flags;
1515
1516 spin_lock_irqsave(&rq->lock, flags);
-----------------------
I suspect this soft lock ups are due to rq->lock contention. Thanks
Sharyathi