[Bug 1798127] Re: CPU Soft Lockups when stress-ng stack stressor runs with M.2 NVMe as root FS

** Tags added: kernel-fixed-upstream

** Changed in: linux (Ubuntu Bionic)
Status: Triaged => Confirmed

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https://bugs.launchpad.net/bugs/1798127

Title:
CPU Soft Lockups when stress-ng stack stressor runs with M.2 NVMe as
root FS

Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Bionic:
Confirmed

Bug description:
This was reported by a hardware partner. The system set up is a
server with 512GB RAM and an M.2 NVMe drive as the root
filesystem/boot device.

Per the customer, when running the certification Memory Stress test
(utilizing several stress-ng stressors run in sequence) the system
freezes with CPU Soft Lockup errors appearing on console whe the
"stack" stressor is run.

Tester has tried with 2.5" SATA (1TB), 2.5" NVMe (800GB), and M.2 NVMe
(1.9TB).

So far, this only seems to affect the 4.15 kernel. The tester has
tried using the 2.5" SATA SSD as the RootFS/Boot device and the tests
pass on all attempts. It is ONLY when using the M.2 NVMe as the root
/ boot device that the tests cause a lockup. The tester is re-trying
now with the 2.5" NVMe device to see if this only occurs with the M.2
NVMe.

The tester has tried this on the following while using the M.2 NVMe as the rootFS/Boot device:
Test run #1 – 16.04.5 at kernel 4.15; Result: Failed stress-ng memory on stack stressor
Test run #2 – 18.04.1 at kernel 4.15; Result: Failed stress-ng memory on stack stressor
Test run #3 – 16.04.5 at kernel 4.4; Result: Passed stress-ng memory test

The stress-ng command invoked at the time the soft lockups occur is
this:

'stress-ng -k --aggressive --verify --timeout 300 --stack 0'

This can be reproduced by running the memory_stress_ng test script
from the cert suite:

sudo /usr/lib/plainbox-provider-certification-
server/bin/memory_stress_ng

It may be more easily reproducible running the stack stressor alone,
or the whole memory stress script without dealing with Checkbox.

UPDATE: The tester also confirms that the 2.5" NVMe drives also fail
with the 4.15 kernel and pass with the 4.4 kernel. The SSD works on
all kernels.

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