KFENCE aims at production environments, but it does not allow enabling
after system startup because kfence_pool only alloc pages from memblock.
Consider the following production scene:
At first, for performance considerations, production machines do not
enable KFENCE.
However, after running for a while, the kernel is suspected to have
memory errors. (e.g., a sibling machine crashed.)
So other production machines need to enable KFENCE, but it's hard for
them to reboot.

The 1st patch allows re-enabling KFENCE if the pool is already
allocated from memblock.

The 2nd patch applies the main part.

Tianchen Ding (2):
  kfence: Allow re-enabling KFENCE after system startup
  kfence: Alloc kfence_pool after system startup

 mm/kfence/core.c | 106 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 87 insertions(+), 19 deletions(-)

-- 
2.27.0