The Z3fold allocator for compressed pages was quietly deprecated several months ago with users encouraged to use zsmalloc instead. With no one vocally objecting, the Z3fold allocator code is now being positioned for removal from the Linux kernel source tree.

Z3fold is an allocator for compressed pages whereby you can achieve up to three compressed pages per physical page. Moving forward users are encouraged to use the Zsmalloc allocator. The main downside with zsmalloc is requiring an MMU whereas Z3fold can get by without a memory management unit. Zsmalloc used to have worse latency than Z3fold but that's been found to no longer be the case. Z3fold on the other hand has been found to contain some latent bugs and can have higher swap use than zsmalloc.

With Z3fold having been deprecated for two kernel cycles without complaint, there are now patches pending to remove the Z3fold from the Linux kernel.

[1]This patch goes ahead and carries out that removal. The Zbud deprecation/removal is also expected to happen coming soon as it offers only small latency gains but with much memory waste over Zsmalloc. If no objections are raised, this patch removing Z3fold could potentially land for the Linux v6.15 kernel in the spring.



[1] https://lore.kernel.org/lkml/Z5gdpStVzlM_fRLT@google.com/