[PATCH v3 0/2] provide the flexibility to enable KFENCE

[Tianchen Ding <dtcccc@linux.alibaba.com>]

This is v3 for (re-)enabling KFENCE.

If CONFIG_CONTIG_ALLOC is not supported, we fallback to try
alloc_pages_exact(). Allocating pages in this way has limits about
MAX_ORDER (default 11). So we will not support allocating kfence pool
after system startup with a large KFENCE_NUM_OBJECTS.

When handling failures in kfence_init_pool_late(), we pair
free_pages_exact() to alloc_pages_exact() for compatibility
consideration, though it actually does the same as free_contig_range().

v3:
Use alloc_pages_exact() instead of alloc_contig_pages()
if CONFIG_CONTIG_ALLOC is not defined.

v2: https://lore.kernel.org/all/20220305144858.17040-1-dtcccc@linux.alibaba.com/
Take KFENCE_WARN_ON() into account. Do not allow re-enabling KFENCE
if it once disabled by warn.
Modify func names and comments.

RFC/v1: https://lore.kernel.org/all/20220303031505.28495-1-dtcccc@linux.alibaba.com/

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

 mm/kfence/core.c | 126 +++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 105 insertions(+), 21 deletions(-)

-- 
2.27.0