[PATCH 0/3][SRU][ARTFUL] Fix deadlock on task switches with new microcode
tyhicks at canonical.com
Thu Apr 5 05:51:34 UTC 2018
Some systems experience kernel lockups after updating to the latest
intel-microcode package or when receiving updated microcode from a BIOS update.
In many cases, the lockups occur before users can reach the login screen which
makes it very difficult to debug/workaround.
The most reliable test case currently known is to install the sssd package.
Lockups may occur during package installation (disable IBPB by writing 0 to
/proc/sys/kernel/ibpb_enabled to prevent this from happening). A lockup will
most likely occur just after booting the system up as the lock screen is
The fix is in the task switching code of the kernel so complexity of the change
is relatively high.
The third patch fixes what I think was an incomplete backport of 72be211ba.
That commit added the initialize_tlbstate_and_flush() function but then never
added any callers of that function.
I was hopeful that the third patch would fix a resume from hibernation/sleep
bug (LP: #1748393) but one tester reported that it did not have an effect.
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