[PATCHSET v2 0/2] fstests: fix cpu hotplug mess

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Hi all,

Ritesh and Eric separately reported crashes in XFS's hook function for
CPU hot remove if the remove event races with a filesystem being
mounted.  I also noticed via generic/650 that once in a while the log
will shut down over an apparent overrun of a transaction reservation;
this turned out to be due to CIL percpu list aggregation failing to pick
up the percpu list items from a dying CPU.

Either way, the solution here is to eliminate the need for a CPU dying
hook by using a private cpumask to track which CPUs have added to their
percpu lists directly, and iterating with that mask.  This fixes the log
problems and (I think) solves a theoretical UAF bug in the inodegc code

v2: fix a few put_cpu uses, add necessary memory barriers, and use
    atomic cpumask operations

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.


fstests git tree:
 tests/generic/650 |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

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