Hi! When tuning the HVR-4400 to a DVB-C channel I get this kernel oops: Jan 3 21:59:39 gauss kernel: BUG: unable to handle kernel NULL pointer dereference at 00000000000001a0 Jan 3 21:59:39 gauss kernel: IP: [<ffffffffa019e2c8>] vb2_core_qbuf+0x18/0x200 [videobuf2_core] Jan 3 21:59:39 gauss kernel: PGD bbf99067 PUD b9dbf067 PMD 0 Jan 3 21:59:39 gauss kernel: Oops: 0000 [#1] SMP Jan 3 21:59:39 gauss kernel: Modules linked in: si2165(O) a8293(O) tda10071(O) tea5767(O) tuner(O) cx23885(O) tda18271(O) videobuf2_dvb(O) videobuf2_dma_sg(O) videobuf2_memops(O) frame_vector(PO) videobuf2_v4l2(O) videobuf2_core(O) tveeprom(O) cx2341x(O) v4l2_common(O) videodev(O) media(O) dvb_core(O) rc_core(O) regmap_i2c bluetooth rtl8192cu rtl_usb rtl8192c_common uas rtlwifi usb_storage snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec x86_pkg_temp_thermal kvm_intel kvm snd_hwdep snd_hda_core [last unloaded: si2165] Jan 3 21:59:39 gauss kernel: CPU: 2 PID: 29081 Comm: vb2-cx23885[0] Tainted: P W O 4.2.8-gentoo #1 Jan 3 21:59:39 gauss kernel: Hardware name: MEDION E2050 2391/H81H3-EM2, BIOS H81EM2W08.308 08/25/2014 Jan 3 21:59:39 gauss kernel: task: ffff880087533300 ti: ffff880101ca8000 task.ti: ffff880101ca8000 Jan 3 21:59:39 gauss kernel: RIP: 0010:[<ffffffffa019e2c8>] [<ffffffffa019e2c8>] vb2_core_qbuf+0x18/0x200 [videobuf2_core] Jan 3 21:59:39 gauss kernel: RSP: 0018:ffff880101cabe28 EFLAGS: 00010246 Jan 3 21:59:39 gauss kernel: RAX: ffff880087533300 RBX: ffff8800a9c98000 RCX: 00000000000003a5 Jan 3 21:59:39 gauss kernel: RDX: ffff8800a9c98000 RSI: 0000000000005e00 RDI: ffff88011995e828 Jan 3 21:59:39 gauss kernel: RBP: ffff880101cabe48 R08: 0000000000000007 R09: 0000000000000001 Jan 3 21:59:39 gauss kernel: R10: 0000000000000000 R11: ffff88011995e828 R12: ffff88011a457780 Jan 3 21:59:39 gauss kernel: R13: 0000000000000000 R14: ffff8800a9c98000 R15: ffff88011995e828 Jan 3 21:59:39 gauss kernel: FS: 0000000000000000(0000) GS:ffff88011fb00000(0000) knlGS:0000000000000000 Jan 3 21:59:39 gauss kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Jan 3 21:59:39 gauss kernel: CR2: 00000000000001a0 CR3: 00000000b9e63000 CR4: 00000000001406e0 Jan 3 21:59:39 gauss kernel: Stack: Jan 3 21:59:39 gauss kernel: ffff8800a9c98000 ffff88011a457780 0000000000000000 0000000000000000 Jan 3 21:59:39 gauss kernel: ffff880101cabeb8 ffffffffa019f83c ffff88004550bb58 ffff880087533300 Jan 3 21:59:39 gauss kernel: ffff8800a9c9a400 0000000000cac000 ffff88011995e828 ffffffffa019f610 Jan 3 21:59:39 gauss kernel: Call Trace: Jan 3 21:59:39 gauss kernel: [<ffffffffa019f83c>] vb2_thread+0x22c/0x3c0 [videobuf2_core] Jan 3 21:59:39 gauss kernel: [<ffffffffa019f610>] ? vb2_core_dqbuf+0x5a0/0x5a0 [videobuf2_core] Jan 3 21:59:39 gauss kernel: [<ffffffffa019f610>] ? vb2_core_dqbuf+0x5a0/0x5a0 [videobuf2_core] Jan 3 21:59:39 gauss kernel: [<ffffffff8106c464>] kthread+0xc4/0xe0 Jan 3 21:59:39 gauss kernel: [<ffffffff8106c3a0>] ? kthread_worker_fn+0x150/0x150 Jan 3 21:59:39 gauss kernel: [<ffffffff8189d04f>] ret_from_fork+0x3f/0x70 Jan 3 21:59:39 gauss kernel: [<ffffffff8106c3a0>] ? kthread_worker_fn+0x150/0x150 Jan 3 21:59:39 gauss kernel: Code: c7 a8 1d 1a a0 e8 12 67 6f e1 31 c0 e9 70 ff ff ff 66 90 55 89 f6 48 89 e5 41 56 41 55 41 54 53 49 89 d6 4c 8b ac f7 80 00 00 00 <41> 8b 95 a0 01 00 00 83 fa 01 0f 84 fb 00 00 00 49 89 fc 0f 82 Jan 3 21:59:39 gauss kernel: RIP [<ffffffffa019e2c8>] vb2_core_qbuf+0x18/0x200 [videobuf2_core] Jan 3 21:59:39 gauss kernel: RSP <ffff880101cabe28> Jan 3 21:59:39 gauss kernel: CR2: 00000000000001a0 Jan 3 21:59:39 gauss kernel: ---[ end trace f45084629c26b0e2 ]--- It oopses in vb2_core_qbuf+0x18 addr2line shows this: media_build/v4l/videobuf2-core.c:1377 >From decodecode: 13: 55 push %rbp 14: 89 f6 mov %esi,%esi 16: 48 89 e5 mov %rsp,%rbp 19: 41 56 push %r14 1b: 41 55 push %r13 1d: 41 54 push %r12 1f: 53 push %rbx 20: 49 89 d6 mov %rdx,%r14 23: 4c 8b ac f7 80 00 00 mov 0x80(%rdi,%rsi,8),%r13 2a: 00 2b:* 41 8b 95 a0 01 00 00 mov 0x1a0(%r13),%edx <-- trapping instruction 32: 83 fa 01 cmp $0x1,%edx 35: 0f 84 fb 00 00 00 je 0x136 3b: 49 89 fc mov %rdi,%r12 1375: vb = q->bufs[index]; 1376: 1377: switch (vb->state) { The value vb (r13) is equal to 0 here. I bisected the oops to this commit: 70433a152f0058404afb5496a9329e4e26b127df is the first bad commit commit 70433a152f0058404afb5496a9329e4e26b127df Author: Junghak Sung <jh1009.sung@xxxxxxxxxxx> Date: Tue Nov 3 08:16:41 2015 -0200 [media] media: videobuf2: Refactor vb2_fileio_data and vb2_thread Replace v4l2-stuffs with common things in struct vb2_fileio_data and vb2_thread(). Signed-off-by: Junghak Sung <jh1009.sung@xxxxxxxxxxx> Signed-off-by: Geunyoung Kim <nenggun.kim@xxxxxxxxxxx> Acked-by: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx> Acked-by: Inki Dae <inki.dae@xxxxxxxxxxx> Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> Signed-off-by: Hans Verkuil <hansverk@xxxxxxxxx> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> :040000 040000 58629432fa60b955a899c49e4cd70fecbc6529eb f93e018351853d33208a464a21256f2b3374f72b M drivers Regards Matthias -- 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