Public bug reported:
Create VM on Azure using Canonical UbuntuServer 14.04.5-LTS latest using
size Standard DS2 v2
Install kexec-tools kdump-tools makedumpfile, configure boot kernel
parameter crashkernel=512M
Run sed -i 's/USE_KDUMP=0/USE_KDUMP=1/g' /etc/default/kdump-tools and
sed -i 's/LOAD_KEXEC=true/LOAD_KEXEC=false/g' /etc/default/kexec
Reboot VM, make sure crash kernel memory reserved successfully
Trigger a crash by run echo 1 > /proc/sys/kernel/sysrq, then echo c >
/proc/sysrq-trigger, VM will reboot automatically and after reboot,
check crash dump is generated under /var/crash
Install linux-azure kernel
Enable private-ppa canonical-kernel-esm
Install kernel linux-azure, reboot VM, kernel version 4.15.0-1084-azure
Trigger a crash by run echo 1 > /proc/sys/kernel/sysrq, then echo c >
/proc/sysrq-trigger, VM entered into a hung status.
Attach whole serial console
[ 65.452007] INFO: rcu_sched detected stalls on CPUs/tasks:
[ 65.456004] 1-...!: (0 ticks this GP) idle=488/0/0 softirq=1/1 fqs=0
[ 65.456004] (detected by 0, t=15002 jiffies, g=707, c=706, q=8457)
[ 65.456004] rcu_sched kthread starved for 15002 jiffies! g707 c706 f0x0
RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=1
[ 360.020026] INFO: rcu_sched detected stalls on CPUs/tasks:
[ 360.024015] 1-...!: (10 GPs behind) idle=b34/0/0 softirq=1/1 fqs=1
[ 360.024015] (detected by 0, t=15002 jiffies, g=717, c=716, q=6429)
[ 360.024015] rcu_sched kthread starved for 15000 jiffies! g717 c716 f0x0
RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=1
[ 420.048010] INFO: rcu_sched detected stalls on CPUs/tasks:
[ 420.052006] 1-...!: (0 ticks this GP) idle=f94/0/0 softirq=1/1 fqs=0
[ 420.052006] (detected by 0, t=15002 jiffies, g=718, c=717, q=6429)
[ 420.052006] rcu_sched kthread starved for 15002 jiffies! g718 c717 f0x0
RCU_GP_WAIT_FQS(3) ->state=0x402 ->cpu=1
** Affects: linux-azure (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1882623
Title:
VM enter into hung status after triggering a crash
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