On Thu, 30 Jun 2022 09:47:15 +0800 Feng Tang <feng.tang@xxxxxxxxx> wrote: > kmalloc's API family is critical for mm, with one shortcoming that > its object size is fixed to be power of 2. When user requests memory > for '2^n + 1' bytes, actually 2^(n+1) bytes will be allocated, so > in worst case, there is around 50% memory space waste. > > We've met a kernel boot OOM panic, and from the dumped slab info: > > [ 26.062145] kmalloc-2k 814056KB 814056KB > > >From debug we found there are huge number of 'struct iova_magazine', > whose size is 1032 bytes (1024 + 8), so each allocation will waste > 1016 bytes. Though the issue is solved by giving the right(bigger) > size of RAM, it is still better to optimize the size (either use > a kmalloc friendly size or create a dedicated slab for it). Well that's nice, and additional visibility is presumably a good thing. But what the heck is going on with iova_magazine? Is anyone looking at moderating its impact?
