kfence: the great schism

[ramosian-glider]

Split kfence.c into kfence_core.c (pool allocator, error reporting, debugfs) and kfence_steal.c (heartbeat timer and freelist stealing mechanism). This will ease trying other sampling approaches, e.g. the naive counter-based one. Those implementations will need to implement their own kfence_init() and use the API declared in kfence_core.h.

The change also helped discover an incorrect lock having been used in obj_show().

Signed-off-by: Alexander Potapenko glider@google.com

[melver]

Nice, thanks!

Does it make sense to move to mm/kfence/ at this point?

[ramosian-glider]

Yes, probably. I thought for two files it didn't make sense, but that was before kfence_core.h. I'll create the dir as well.