Hello RT-Users! I am using preemption-patches with such an uname: client30:/tmp# uname -a Linux client30 2.6.29.5-rt22-486-voyage #1 PREEMPT RT Fri Jul 17 08:55:16 GMT 2009 i586 GNU/Linux I did let an ALIX-board with an ALSA-application run for one night and I ran into this bug: BUG: unable to handle kernel NULL pointer dereference at 4 IP: [<d0131749>] snd_pcm_period_elapsed+0x11/0x1e3 [snd_pcm] *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: /sys/class/net/lo/operstate Modules linked in: ipv6 dm_mod ledtrig_timer ledtrig_heartbeat led_class scx2002 Pid: 3148, comm: IRQ-11 Tainted: P (2.6.29.5-rt22-486-voyage #1) EIP: 0060:[<d0131749>] EFLAGS: 00010292 CPU: 0 EIP is at snd_pcm_period_elapsed+0x11/0x1e3 [snd_pcm] EAX: 00000000 EBX: ce9c1f38 ECX: ce9c1f38 EDX: cf053110 ESI: ce9c1f20 EDI: cf333400 EBP: ce4bff64 ESP: ce4bff4c DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 preempt:00000001 Process IRQ-11 (pid: 3148, ti=ce4bf000 task=cf053110 task.ti=ce4bf000) Stack: ce4bff5c 00000000 ceabe89c ce9c1f38 ce9c1f20 00000004 ce4bff7c d01dc1ba cf010210 cf07e7a0 00000000 0000000b ce4bff9c c01351da 0000000b 00000000 00000000 c0392c10 0000000b 0000000b ce4bffb4 c0135596 cf07e7a0 c0392c10 Call Trace: [<d01dc1ba>] ? snd_cs5535audio_interrupt+0x80/0xf6 [snd_cs5535audio] [<c01351da>] ? handle_IRQ_event+0x45/0xb6 [<c0135596>] ? thread_simple_irq+0x43/0x7c [<c0135b5c>] ? do_irqd+0x95/0x247 [<c0135ac7>] ? do_irqd+0x0/0x247 [<c012501c>] ? kthread+0x39/0x61 [<c0124fe3>] ? kthread+0x0/0x61 [<c0103047>] ? kernel_thread_helper+0x7/0x10 Code: ff ff 59 43 8b 0c 9d 80 88 13 d0 83 f9 ff 75 d0 8d 65 f4 31 c0 5b 5e 5f 5 EIP: [<d0131749>] snd_pcm_period_elapsed+0x11/0x1e3 [snd_pcm] SS:ESP 0068:ce4bfc CR2: 00000000000001f4 ---[ end trace ab661b3967ef3988 ]--- Clocksource tsc unstable (delta = 186926649 ns) If you need any additional informations about this problem, just let me know. I hope, this will help you in improving the preemtion-patches. In addition, a fix of my problem would be nice ;-) Kind regards, Dennis -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html