Postings by wuzhouhui

What happened if install a el7 package on a el6 system


Recently, I encountered a interesting phenomenon that CentOS 6.3
running as normal even if I (my colleague, actually) installed a
kernel that build for CentOS 7.x (e.g. kernel-3.10.0-327.el7.x86_64.rpm).

I found kernel is mismatch accidentally when I using "uname -r" to
check kernel version. So my question is what the harmness we will
get if I install a el7 rpm into a el6 system?


Who is responsible to load NIC driver when boot up


I have a small question about NIC driver (e.g. i40e) loading. Who is
responsible to load i40e driver? And how does he knows we should load
i40e, instead of ixgbe?


rpmbuild how to know we are building kernel module package


When I build a mpt3sas rpm package, I found something interesting:
1. package name is prefixed with kmod- automatically

udev rename NIC failed


Sometimes, I found one of my Mellanox NIC renamed to rename6, instead
of eth1. The right names of NICs in my system should be:
eth0 Mellanox NIC
eth1 Mellanox NIC
eth2 Intel NIC
eth3 Intel NIC
eth4 Intel NIC
eth5 Intel NIC
eth0 and eth1 will combined as bond1 with mode 4.

How to specify kernel version when restart kdump


Is there a way to specify kernel version when (re)start kdump
service? Suppose I have install a new kernel and kdump will
generate kdump.img for new kernel in next boot. But I want kdump
to generate kdump.img for new kernel immediately, is it possible?


do not uninstall old when yum install new


I have a specific needs that requires yum do not to uninstall old
version when install new one. For example, I found that
yum install kernel
will install new kernel, and old kernel will remained. But
yum install <something-else>
will uninstall old version after install new one, how to disable it?


How to get unrelease kernel, e.g. 3.10.0-341.el7


I cloned <a href="" title=""></a> and found that it
only contains kernel version that CentOS released. So how do I get
the kernel version that CentOS not release officialy, e.g.
3.10.0-341.el7 and 3.10.0-383.el7 (some kernel version I found
in kernel.spec's changelog)?


Where is centos6.x kernel git repo

Hi, I following the steps described in <a href="" title=""></a>
to get centos7.x kernel repo. But I'm wondering how to get centos6.x
kernel repo. Because when checkout branch 'c6' and found that there is


centos 7.5 crashed, kernel BUG at net/core/skbuff.c:3668!

[ 176.025679] random: crng init done
[ 411.168635] netem: version 1.3
[ 456.059840] ------------[ cut here ]------------
[ 456.059849] WARNING: CPU: 4 PID: 1918 at net/ipv4/tcp_output.c:1048 tcp_set_skb_tso_segs+0xeb/0x100
[ 456.059851] Modules linked in: sch_netem cirrus ttm drm_kms_helper crc32_pclmul syscopyarea ghash_clmulni_intel sysfillrect sysimgblt fb_sys_fops aesni_intel lrw ppdev gf128mul drm glue_helper ablk_helper cryptd parport_pc parport i2c_piix4 virtio_balloon i2c_core joydev pcspkr ip_tables ext4 mbcache jbd2 ata_generic pata_acpi ata_piix virtio_console virtio_net vi

Fw: Re: [SPDK] VM boot failed sometimes if using vhost-user-blk with spdk

Forwarded to centos mailing list

Sent Time: 2018-10-30 14:06:00 (Tuesday)
Cc: <a href="mailto: ... at centos dot org"> ... at centos dot org</a>, <a href="mailto:qemu- ... at nongnu dot org">qemu- ... at nongnu dot org</a>

I enable debug of systemd-udevd by changing guest's /etc/udev/udev.conf to this:
and regenerate initramfs. Then, we can get more message about this issue.

CentOS 7.4 paniced when running LTP tests

LTP version: ltp-full-20180118
Kernel version: 3.10.0-693.el7.x86_64
Reproduce procedure:
1. cd ltp-full-20180118; ./configure; make && make install

How to update modules in iniramfs fastly

I know dracut can update modules in initramfs, but I think it is too
slow. So I'm wondering what is the fastest way to update modules in
initramfs of CentOS 7?


Network broke for a while when libvirtd start

When start service libvirtd by

service libvirtd start

the network will broke for a while and then reconnected.

Adjust type of rw in submit_bio from int to unsigned long

Hi, I am a developer who worked on CentOS. Recently I am working on porting one of my
block drivers from CentOS 6.x to CentOS 7.x.

soft lockup after set multicast_router of bridge and it's port to 2

After I set multicast_router of bridge and it's port to 2, like following:
echo 2 > /sys/devices/virtual/net/eth81/bridge/multicast_router
echo 2 > /sys/devices/virtual/net/bond2/brport/multicast_router
Then soft lockup occured:
Message from syslogd@node-0 at Jan 9 15:47:12 ...
kernel:BUG: soft lockup - CPU#0 stuck for 61s!

Can't see register value in crash vmcore

Kernel crashed by panic("string"), but I can't see any register in vmcore:

crash> bt
PID: 53331 TASK: ffff880c523ed540 CPU: 2 COMMAND: "bw_sd-ar-7-0_2"
#0 [ffff880c4f12f978] machine_kexec at ffffffff81038ed9
#1 [ffff880c4f12f9d8] crash_kexec at ffffffff810c5a82
#2 [ffff880c4f12faa8] panic at ffffffff815113b2
#3 [ffff880c4f12fb28] sd_submit_bio at ffffffffa0747a02 [sd]
#4 [ffff880c4f12fb68] submit_clone_bio at ffffffffa0747d2b [sd]
#5 [ffff880c4f12fb78] split_and_submit_bio_for_cbd at ffffffffa0747ec9 [sd]
#6 [ffff880c4f12fbf8] sd_make_request at ffffffffa074c812 [sd]
#7 [ffff880c4

Null deference panic in CentOS-6.5


I got a panic when running CentOS-6.5:

crash> bt
PID: 106074 TASK: ffff8839c1e32ae0 CPU: 4 COMMAND: "flushd4[cbd-sd-"
#0 [ffff8839c2a91900] machine_kexec at ffffffff81038fa9
#1 [ffff8839c2a91960] crash_kexec at ffffffff810c5992
#2 [ffff8839c2a91a30] oops_end at ffffffff81515c90
#3 [ffff8839c2a91a60] no_context at ffffffff81049f1b
#4 [ffff8839c2a91ab0] __bad_area_nosemaphore at ffffffff8104a1a5
#5 [ffff8839c2a91b00] bad_area_nosemaphore at ffffffff8104a273
#6 [ffff8839c2a91b10] __do_page_fault at ffffffff8104a9bf
#7 [ffff8839c2a91c30] do_page_fault at ffffffff8