On Thu, 2011-03-03 at 21:06 -0500, Andy Walls wrote: > Hi, > > I got a BUG when loading the cx18.ko module (which in turn requests the > cx18-alsa.ko module) on a kernel built from this repository > > http://git.linuxtv.org/media_tree.git staging/for_v2.6.39 > > which I beleive is based on 2.6.38-rc2. [snip] > So here is my transcription of a fuzzy digital photo of the screen: > > kernel BUG at /home/andy/cx18dev/git/media_tree/mm/mmap.c:2309! > invalid opcode: 0000 [#1] SMP > last sysfs file: /sys/module/snd_pcm/initstate > Modules linked in: tda9887 tda8290 mxl5005s s5h1409 tuner_simple ... > ... > Pid: 2580, comm: udevd Not tainted 2.6.38-rc2-cx18-vb2-proto+ > RIP: 0010:[<ffffffff810eb50b>] [<ffffffff810eb50b>] exit_mmap+0x10f/0x11e > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0020000000000000 > RDX: 0000000000160011 RSI: ffffea____c42___ RDI: 0000000000000202 > RBP: ffff____18c1f_58 R08: ffff____________ R09: 0000000000000004 > R10: ffff_______bb_38 R11: 0000000000000000 R12: ffff____344a6680 > R13: 00007fff22______ R14: ffff____________ R15: 0000000000000001 > ... > CR2: 0000000000000000 ... > .... > Process udevd (pid: 25__, threadinfo ffff________, ... > Stack: > 000000000000015e ffff00003bc0e1d0 0000000000000246 .... > ..... > Call Trace: > ... mmput+0x63/0xcf > ... exit_mm+0x132/0x13f > ... do_exit+0x238/0x749 > ... ? __dequeue_signal+0xfa/0x12f > ... do_group_exit+0x7d/0xa5 > ... get_signal_to_deliver+0x371/0x395 > ... do_signal+0x72/0x692 > ... ? do_page_fault+0x24a/0x391 > ... ? printk+0x41/0x47 > ... ? sigprocmask+0xa3/0xcd > ... do_notify_resume+0x2c/0x64 > ... retint_signal+0x48/0x8c > > Code: ff ff 48 8b 7d d8 4c 89 ea 31 f6 e8 3e fe ff ff 48 89 df e8 78 fe > ff ff 48 85 c0 48 89 c3 75 f0 49 83 bc 24 e0 00 00 00 00 74 04 <0f> 0b > eb fe 48 83 c4 18 5b 41 5c 41 5d c9 c3 55 48 89 e5 41 57 > RIP [<ffffffff810eb50b>] exit_mmap+0x10f/0x11e > RSP <ffff880018c1fc28> > general protection fault: 0000 [#2] SMP > last sysfs file: /sys/devices/virtual/sound/card2/uevent > CPU 1 > Modules linked in: cx18-alsa tda9887 tda8290 mxl5005s s5h1409 > tuner_simple tuner_types cs5345 tuner cx18 dvb_core cx2341x v4l2_common > videodev v4l2_compat_ioctl32 I'm dumping all my previous assumtpions about this BUG. After a bit of reading, all I can say is that it's a page table deallocation problem at process exit. After all the page table deallocations on exit, mm->nr_ptes is still > 0, and that's a bad thing. It apparently happened in a child udevd exiting shortly after cx18.ko loaded. The cx18 driver allocating large amounts kernel memory for DMA buffers upon load may be related to triggering the problem, but I doubt it is a root cause of the BUG. This monsterous thread from 5 years ago is somewhat enlightening: http://lkml.indiana.edu/hypermail/linux/kernel/0503.2/1680.html http://lkml.indiana.edu/hypermail/linux/kernel/0503.2/1787.html so it gives me a place to start looking for the problem. Any advice on what data to collect is appreciated. Regards, Andy -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
