SLOB Allocator Being Deprecated With Linux 6.2

Following the recent developer talk of looking to drop SLOB from the Linux kernel, this simple allocator is being deprecated come Linux 6.2.

The SLAB allocator pull request has been submitted ahead of the Linux 6.2 merge window opening next week. Most notable is that SLOB is being deprecated while SLAB is also expected to be deprecated soon. Linux users should ensure they are using the SLUB allocator moving forward.

The pull request notes:

"The SLOB allocator adds maintenance burden and stands in the way of API improvements. Deprecate it by renaming the config option (to make users notice) to CONFIG_SLOB_DEPRECATED with updated help text. SLUB should be used instead as SLAB will be the next on the removal list."

The Simple List Of Blocks "SLOB" memory allocator has been around a long time as an alternative to the SLAB and SLUB allocators primarily for small/embedded systems where space efficiency is important.

There are no known users of SLOB still relying on it for its slightly smaller footprint, it's a maintenance burden, and now API improvements can more easily move forward. In helping ease anyone still finding use from SLOB, a SLUB_TINY option is added for limiting SLUB's memory overhead. SLUB_TINY is now used in place of the default kernel configurations where SLOB was previously used, such as for systems with just megabytes of RAM.