[CentOS-virt] kernel-4.9.37-29.el7 (and el6)

On Mon, 17 Jul 2017, Johnny Hughes wrote:

> Are the testing kernels (kernel-4.9.37-29.el7 and kernel-4.9.37-29.el6,
> with the one config file change) working for everyone:
>
> (turn off: CONFIG_IO_STRICT_DEVMEM)

Hello.
Maybe it's not the most appropriate thread or time, but I have been
signalling it before:

4.9.* kernels do not work well for me any more (and for other people
neither, as I know). Last stable kernel was 4.9.13-22.

Since 4.9.25-26 I do often get:
on 3 supermicro servers (different generations):
- memory allocation errors on Dom0 and corresponding lost lost page writes
 	due to buffer I/O error on PV guests
- after such memory allocation error od dom0 I have spotted also:
 	- NFS client hangups on guests (server not responding, still trying => server OK)
 	- iptables lockups on PV guest reboot

on 1 supermicro server:
- memory allocation errors on Dom0 and SATA lockups (many, if not SATA channels at
 	- once):
 	exception Emask 0x0 SAct 0x20 SErr 0x0 action 0x6 frozen
 	hard resetting link
 	failed to IDENTIFY (I/O error, err_mask=0x4)
 	then: blk_update_request: I/O error, dev sd., sector ....


All of these machines have been tested with memtest, no detected memory problems.
No such things occur, when I boot 4.9.13-22
Most of my guests are centos 6 x86_64, bridged.

Do anyone had such problems, dealt with it somehow?


Since spotting these errors I have done many tests, compiled and tested to
point out single code change (kernel version, patch) - no conclusions yet.

But one has changed much between 4.9.13 and 4.9.25: kernel size and
configuration.
4.9.13 size was 6MB and 4.9.24 is 7.1MB. Many modules have been
compiled into kernel, here is shortened, but significant list:
- iptables (NETFILTER_XTABLES, IP_NF_FILTER, IP_NF_TARGET_REJECT)
- SATA_AHCI
- ATA_AHCI (PATA, what a heck?)
- FBDEV_FRONTEND
- HID_MAGICKMOUSE
- HID_NTRIG
- USB_XHCI
- INTEL_SMARTCONNECT

Do we really need these compiled into dom0 kernel?

I assume, that the biggest change in size is due to yama and CRYPTO_*, and
it is not going to change.

Regards,

-- 
Piotr Gackiewicz
Intertele S.A. - operator systemów ITL.PL i DOMENY.ITL.PL
al. T. Rejtana 10, 35-310 Rzeszów
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