Questions[dmesg](ubuntu)

What is the meaning of these messages in dmesg?

[184608.460680] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]                                                                                               
[185208.535291] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]                                                                                               
[185808.593951] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]                                                                                               
[187008.711644] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]                                                                                               
[188808.928580] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]                                                                                               
[190009.066819] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]                                                                                               
[191209.156346] nouveau 0000:01:00.0: fb: trapped read at 0101400000 on channel -1 [3fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]     

Is it a hardware or software problem?

Few days back, I ran dmesg on my terminal to see this line Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7

Sometimes, as in the image below, the kernel ring buffer only prints this line repeatedly!

What is this diagnostic message regarding, and what does it mean? What should I be doing if it is something that I should be dealing with immediately?

I'm on a clean install of Ubuntu Mate 18.04, the system itself is working with no issues, but I am running dmesg to look at errors and warnings. I like to try to get them all dealt with if possible even if they aren't causing obvious issues right now.

I have an Nvidia card running driver 390.48.

I've got most of the issues dealt with, but one that pops up four times says this:

PKCS#7 signature not signed with a trusted key

Here are +/- three lines in dmesg for context for two of the occurrences (the second one actually captures two):

[    1.157284] ata3: SATA max UDMA/133 abar m2048@0xdf34b000 port 0xdf34b200 irq 126
[    1.157285] ata4: SATA max UDMA/133 abar m2048@0xdf34b000 port 0xdf34b280 irq 126
[    1.157535] e1000e 0000:00:1f.6: Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode
[    1.168128] PKCS#7 signature not signed with a trusted key
[    1.168135] nvidia: loading out-of-tree module taints kernel.
[    1.168138] nvidia: module license 'NVIDIA' taints kernel.
[    1.168138] Disabling lock debugging due to kernel taint

and:

[    1.175479] nvidia-nvlink: Nvlink Core is being initialized, major device number 238
[    1.175681] nvidia 0000:01:00.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=io+mem
[    1.175734] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  390.48  Thu Mar 22 00:42:57 PDT 2018 (using threaded interrupts)
[    1.180047] PKCS#7 signature not signed with a trusted key
[    1.181035] nvidia-modeset: Loading NVIDIA Kernel Mode Setting Driver for UNIX platforms  390.48  Wed Mar 21 23:48:34 PDT 2018
[    1.181409] PKCS#7 signature not signed with a trusted key
[    1.181814] [drm] [nvidia-drm] [GPU ID 0x00000100] Loading driver

The line in question is the PKCS line, I understand the driver will "taint" the kernel. From the context it seems like the PKCS warnings are related to the Nvidia driver. Is that expected? This is the driver obtained from the Ubuntu repository, not independently from Nvidia, if that makes a difference. Usually I can look up the Nvidia-specific errors and warnings (which are usually harmless) but this one I didn't find anything.

I'm getting these errors ramdomly, and I don't know if its normal or not.

[39441.061856] ata3.00: failed to read SCR 1 (Emask=0x40)
[39441.061866] ata3.01: failed to read SCR 1 (Emask=0x40)
[39441.061892] ata3.15: exception Emask 0x10 SAct 0x0 SErr 0x280100 action 0x6 frozen
[39441.061897] ata3.15: irq_stat 0x08000000, interface fatal error
[39441.061904] ata3.15: SError: { UnrecovData 10B8B BadCRC }
[39441.061910] ata3.00: exception Emask 0x100 SAct 0x0 SErr 0x0 action 0x6 frozen
[39441.061917] ata3.01: exception Emask 0x100 SAct 0xe SErr 0x0 action 0x6 frozen
[39441.061923] ata3.01: failed command: READ FPDMA QUEUED
[39441.061933] ata3.01: cmd 60/a8:08:b0:48:62/00:00:00:00:00/40 tag 1 ncq 86016 in
[39441.061940] ata3.01: status: { DRDY }
[39441.061944] ata3.01: failed command: READ FPDMA QUEUED
[39441.061953] ata3.01: cmd 60/a8:10:b0:49:62/00:00:00:00:00/40 tag 2 ncq 86016 in
[39441.061959] ata3.01: status: { DRDY }
[39441.061963] ata3.01: failed command: READ FPDMA QUEUED
[39441.061972] ata3.01: cmd 60/58:18:58:4a:62/00:00:00:00:00/40 tag 3 ncq 45056 in
[39441.061978] ata3.01: status: { DRDY }
[39441.061987] ata3.15: hard resetting link
[39441.608302] ata3.15: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[39441.609090] ata3.00: hard resetting link
[39441.929246] ata3.00: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
[39441.929333] ata3.01: hard resetting link
[39442.249184] ata3.01: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
[39442.263242] ata3.00: configured for UDMA/133
[39442.277570] ata3.01: configured for UDMA/133
[39442.277725] ata3: EH complete

I'm also pasting smartctl -a for sda, sdb and sdc.

Thanks in advance for your help.

I'm experiencing some problems with drive cache and I don't know what's causing these problems. This is my dmesg:

[11690.011238] sd 6:0:0:0: [sdb] Asking for cache data failed
[11690.011248] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11741.720851] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
[11741.722965] sd 6:0:0:0: [sdb] Asking for cache data failed
[11741.722975] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11793.433011] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
[11793.435347] sd 6:0:0:0: [sdb] Asking for cache data failed
[11793.435356] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11845.140846] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
[11845.143098] sd 6:0:0:0: [sdb] Asking for cache data failed
[11845.143102] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11896.856723] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled

There are hundreds of these lines. It is happening since I've installed Ubuntu 12.04 64bit beta2 from my pendrive. Now I don't have anything at /dev/sdb. I don't know if these errors are making my system less responsive, but I think that dmesg shouldn't look like this.

My kernel version: 3.2.0-24-generic.

Do you have any idea how to solve it?

Thank you in advance.