On Mon, Apr 11, 2022 at 04:35:46PM -0700, Song Liu wrote: > Huge page backed vmalloc memory could benefit performance in many cases. > Since some users of vmalloc may not be ready to handle huge pages, > VM_NO_HUGE_VMAP was introduced to allow vmalloc users to opt-out huge > pages. However, it is not easy to add VM_NO_HUGE_VMAP to all the users > that may try to allocate >= PMD_SIZE pages, but are not ready to handle > huge pages properly. This is a good place to document what the problems are, and how they are hard to track down (e.g. because the allocations are passed down I/O stacks) > > Replace VM_NO_HUGE_VMAP with an opt-in flag, VM_ALLOW_HUGE_VMAP, so that > users that benefit from huge pages could ask specificially. > > Also, replace vmalloc_no_huge() with opt-in helper vmalloc_huge(). We still need to find out what the primary users of the large vmalloc hashes was and convert them. > +extern void *vmalloc_huge(unsigned long size) __alloc_size(1); No need for the extern. > +EXPORT_SYMBOL(vmalloc_huge); EXPORT_SYMBOL_GPL for all advanced vmalloc functionality, please.
