Comment 25 for bug 556919

Same here on 15.04

[ 9876.328007] perf interrupt took too long (3213 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
[37825.813778] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [qemu-system-x86:1159]
[37825.813784] Modules linked in: vhost_net vhost macvtap macvlan xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter ip_tables x_tables nls_iso8859_1 intel_rapl ppdev intel_powerclamp snd_hda_codec_hdmi coretemp kvm_intel snd_hda_codec_realtek snd_hda_codec_generic kvm joydev snd_intel_sst_acpi lpc_ich serio_raw snd_hda_intel snd_intel_sst_core snd_hda_controller snd_soc_rt5640 snd_soc_sst_mfld_platform snd_hda_codec snd_soc_rl6231 snd_soc_core snd_hwdep parport_pc snd_compress parport snd_pcm_dmaengine 8250_fintek snd_pcm dw_dmac dw_dmac_core i2c_hid snd_timer mei_txe snd spi_pxa2xx_platform rfkill_gpio mei mac_hid i2c_designware_platform i2c_designware_core soundcore snd_soc_sst_acpi iosf_mbi pwm_lpss_platform shpchp 8250_dw pwm_lpss autofs4 btrfs xor raid6_pq xts gf128mul dm_crypt hid_generic usbhid hid crct10dif_pclmul i915 crc32_pclmul ghash_clmulni_intel cryptd i2c_algo_bit drm_kms_helper psmouse r8169 drm ahci mii libahci video sdhci_acpi sdhci
[37825.813873] CPU: 0 PID: 1159 Comm: qemu-system-x86 Tainted: G W 3.19.0-30-generic #34-Ubuntu
[37825.813875] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Q1900B-ITX, BIOS P1.70 11/04/2014
[37825.813878] task: ffff88013956c4b0 ti: ffff8800aa2f8000 task.ti: ffff8800aa2f8000
[37825.813881] RIP: 0010:[<ffffffff817cba92>] [<ffffffff817cba92>] _raw_spin_lock+0x32/0x80
[37825.813889] RSP: 0018:ffff8800aa2fbdc8 EFLAGS: 00000202
[37825.813891] RAX: 0000000000003346 RBX: ffff8800acb2a0d0 RCX: 0000000000000002
[37825.813894] RDX: 0000000000005600 RSI: 0000000000005602 RDI: ffffc9001074d144
[37825.813896] RBP: ffff8800aa2fbdc8 R08: 0000000000005602 R09: 0000000000000000
[37825.813898] R10: 0000000000000000 R11: 0000000000000000 R12: dead000000100100
[37825.813900] R13: ffffffff8120a2f0 R14: ffff8800aa2fbc58 R15: ffff880000000000
[37825.813903] FS: 00007f2ee3f02980(0000) GS:ffff88013fc00000(0000) knlGS:0000000000000000
[37825.813906] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[37825.813908] CR2: fffff8a0021db080 CR3: 00000000aa0ee000 CR4: 00000000001027f0
[37825.813910] Stack:
[37825.813912] ffff8800aa2fbe38 ffffffff810f0d4c ffffc9001074d140 ffffc9001074d144
[37825.813916] ffffffff00000004 00007f2ee40dc000 ffff8800933dc000 0000000000000800
[37825.813920] ffff880036176900 00007f2ee40dc800 0000000000000081 0000000000000000
[37825.813924] Call Trace:
[37825.813932] [<ffffffff810f0d4c>] futex_wake+0x9c/0x140
[37825.813937] [<ffffffff810f3a87>] do_futex+0x107/0x5d0
[37825.813943] [<ffffffff81356cf2>] ? common_file_perm+0x42/0xf0
[37825.813947] [<ffffffff810f3fc6>] SyS_futex+0x76/0x170
[37825.813953] [<ffffffff811f5b9a>] ? SyS_write+0x6a/0xb0
[37825.813957] [<ffffffff817cbe8d>] system_call_fastpath+0x16/0x1b
[37825.813959] Code: 89 e5 b8 00 00 02 00 f0 0f c1 07 89 c2 c1 ea 10 66 39 c2 75 04 5d c3 66 90 41 89 d0 0f b7 f2 b8 00 80 00 00 eb 0a 0f 1f 00 f3 90 <83> e8 01 74 35 0f b7 17 89 d1 44 31 c1 81 e1 fe ff 00 00 75 e9