[Bionic] arm64: topology: Avoid checking numa mask for scheduler MC selection
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| linux (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
| Bionic |
Fix Released
|
Undecided
|
Unassigned | ||
Bug Description
[Impact]
The numa mask subset check can often lead to system hang or crash during CPU hotplug and system suspend operation if NUMA is disabled. This is mostly observed on HMP systems where the CPU compute capacities are different and ends up in different scheduler domains. Since cpumask_of_node is returned instead core_sibling, the scheduler is confused with incorrect cpumasks(e.g. one CPU in two different sched domains at the same time) on CPU hotplug.
[Fix]
The following patch fixes this issue:
e156ab71a974 arm64: topology: Avoid checking numa mask for scheduler MC selection
[Test]
-- testcase --
#!/bin/bash
stress-ng -q --vm 100 --vm-bytes 1G --cpu 210 --timeout 2400s --metrics-brief &
pid=$!
for i in {1..210}; do
num=$(
echo "Offline CPU $num"
echo 0 > /sys/devices/
sleep 3s
echo "Online CPU $num"
echo 1 > /sys/devices/
done
kill -9 $pid
----------------
Executed the test case with stock Bionic kernel and with Bionic kernel with patches applied. No system hang or crash was observed. On Cavium CN99XX Thunder X2 system.
[Regression Potential]
Regression tested on Cavium Thunder X2 CN99XX system, and none were found. Regression risk is low.
CVE References
| Ubuntu Kernel Bot (ubuntu-kernel-bot) wrote Missing required logs. | #1 |
| Changed in linux (Ubuntu): | |
| status: | New → Incomplete |
| tags: | added: bionic |
| description: | updated |
| Changed in linux (Ubuntu Bionic): | |
| status: | New → In Progress |
| Changed in linux (Ubuntu): | |
| status: | Incomplete → Invalid |
| Changed in linux (Ubuntu Bionic): | |
| status: | In Progress → Fix Committed |
| Brad Figg (brad-figg) wrote | #2 |
| tags: | added: verification-needed-bionic |
| Manoj Iyer (manjo) wrote | #3 |
| tags: |
added: verification-done-bionic removed: verification-needed-bionic |
| Launchpad Janitor (janitor) wrote | #4 |
| Changed in linux (Ubuntu Bionic): | |
| status: | Fix Committed → Fix Released |
| tags: | added: cscc |
This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:
apport-collect 1797202
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.