On Wed, 9 Jun 2021, Vlastimil Babka wrote:

The handlers of sysfs files alloc_calls and free_calls also currently use this
shared bitmap, but their syscall context makes it straightforward to allocate a
private map before entering locked sections, so switch these processing paths
to use a private bitmap.

Historically that was the case but there were various issues with
recursion via sysfs etc etc. alloca was too stack intensive.... Hopefully
this one will last.