** Description changed:
- 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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https://bugs.launchpad.net/bugs/1747069
Title:
artful 4.13 i386 kernels crash after memory hotplug remove
Status in linux package in Ubuntu:
In Progress
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.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1747069/+subscriptions
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