Hi, On Fri, Apr 8, 2016 at 10:30 AM, Will Deacon <will.dea...@arm.com> wrote: >> > Am I barking up the wrong tree? >> >> I don't think min_order can be negative. Certainly we could enter the >> loop with order == 0 and min_order == 0, though. > > ... and in that case, PageCompound will be false, and we'll call split_page > which won't do anything, so we break out. > >> >> Some examples: >> >> order = 0, min_order = 0 >> -> Want alloc_pages _without_ __GFP_NORETRY. OK >> -> If alloc_pages fails, return NULL. OK >> -> If alloc pages succeeds, don't need splitting since single page. OK > > [...] > >> I think those are all right. Did I mess up? You could certainly >> structure the loop in a different way but you need to make sure you >> handle all of those cases. If you have an alternate structure that >> handles all those, let's consider it. > > Right, I don't think the code is broken, I just think the !order check is > confusing and not needed.
Ah ha! Got it. I didn't dig into split_page() to see that it was a no-op when "order == 0". I just know that the old code didn't call split_page() with order == 0 so I assumed that was wise to keep. If we don't need to keep that then agreed that the "if" test can simply be removed. :) -Doug _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
