| 2018-02-09 10:06:11 |
Colin Ian King |
description |
It seems all of the artful 4.13 are crashing on i386 install when memory hotplug removal is attempted. This crash occurs a few seconds after the removal. I have done a gross bisect back to the first 4.13.0-11 which is also affected. |
== SRU Request, Artful ==
Hotplug removal causes i386 crashes when exercised with the kernel
selftest mem-on-off-test script.
== Fix ==
Revert commit f1dd2cd13c4b (""mm, memory_hotplug: do not associate hotadded memory to zones until online")
Note: A fix occurs in 4.15 however this requires a large set of changes that are way too large to be SRU'able and the least risky way forward is to revert the offending commit.
== Testcase ==
Running the kernel selftest script mem-on-off-test.sh, followed by a sync, followed by re-installing kernel packages will always trigger this issue. Simply running the mem-on-off-test.sh script sometimes won't trigger the problem. I believe this is why we've not seen this happen too frequently with our ADT tests. I can reproduce this in a VM with 4 CPUs and 2GB of memory.
== Regression Potential ==
Reverting this commit does remove some functionality, however this does not regress the kernel compared to previous releases and having a working reliable memory hotplug is the preferred option. This fix does touch some memory hotplug, so there is a risk that this may break this functionality that is not covered by the kernel regression testing. |
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