artful 4.13 i386 kernels crash after memory hotplug remove
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Fix Released
|
High
|
Colin Ian King |
Bug Description
== 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.
CVE References
Changed in linux (Ubuntu): | |
assignee: | nobody → Colin Ian King (colin-king) |
importance: | Undecided → High |
status: | New → Confirmed |
Changed in linux (Ubuntu): | |
status: | Confirmed → In Progress |
description: | updated |
Bisected, bad commit: b3c6858fb172512 f63838523ae7817 ae8adec564 - this is a merge and contains a lot of misc changes across the tree that may have broken this.