RE: [RFC PATCH] x86, entry: Switch stacks on a paranoid entry from userspace

[Luck, Tony]

>> However, I'd like to be very sure this thing doesn't introduce any
>> regressions to the MCA code. So even if Tony's testing passes, I'd like
>> to be very conservative here and stress it more than usual. Because once
>> this thing hits upstream and stuff starts breaking, it'll be a serious
>> PITA reverting it.

The test I left running on Friday was just running the stack-switch asm
patch, without any mce.c changes.  It died at 16000 iterations with the
mce synchronization issue.

This morning I started a new test with all the mce changes (no TIF_MCE_NOTIFY,
just process the recovery in the tail of do_machine_check().

It just passed the 18000 point, and it still going.  In addition I've been throwing
the odd "make -j144" kernel build at the machine so we check out the non-idle
paths too.

-Tony