On Wed, Sep 07, 2022 at 11:49:37PM -0700, Suren Baghdasaryan wrote: > I would really appreciate if everyone could please stick to the > technical side of the conversation. That way we can get some > constructive feedback. Everything else is not helpful and at best is a > distraction. > Maintenance burden is a price we pay and I think it's the prerogative > of the maintainers to take that into account. Our job is to prove that > the price is worth paying. Well said. I'd also like to add - slab.h does look pretty overgrown and messy. We've grown a _lot_ of special purpose memory allocation interfaces, and I think it probably is time to try and wrangle that back. The API complexity isn't just an issue for this patch - it's an issue for anything that has to wrap and plumb through memory allocation interfaces. It's a pain point for the Rust people, and also comes in e.g. the mempool API. I think we should keep going with the memalloc_no*_save()/restore() approach, and extend it to other things: - memalloc_nowait_save() - memalloc_highpri_save() (these two get you GFP_ATOMIC). Also, I don't think these all need to be separate functions, we could have memalloc_gfp_apply() memalloc_gfp_restore() which simply takes a gfp flags argument and applies it to the current PF_MEMALLOC flags. We've had long standing bugs where vmalloc() can't correctly take gfp flags because some of the allocations it does for page tables don't have it correctly plumbed through; switching to the memalloc_*_(save|restore) is something people have been wanting in order to fix this - for years. Actually following through and completing this would let us kill the gfp flags arguments to our various memory allocators entirely. I think we can do the same thing with the numa node parameter - kill kmalloc_node() et. all, move it to task_struct with a set of save/restore functions. There's probably other things we can do to simplify slab.h if we look more. I've been hoping to start pushing patches for some of this stuff - it's going to be some time before I can get to it though, can only handle so many projects in flight at a time :)
