On Tue, Jan 12, 2021 at 10:53:17AM +0100, David Hildenbrand wrote: > That's not sufficient for alternative implementations of pfn_valid(). > > You still need some kind of pfn_valid(pfn) for alternative versions of > pfn_valid(). Consider arm64 memory holes in the memmap. See their > current (yet to be fixed/reworked) pfn_valid() implementation. > (pfn_valid_within() is implicitly active on arm64) > > Actually, I think we should add something like the following, to make > this clearer (pfn_valid_within() is confusing) > > #ifdef CONFIG_HAVE_ARCH_PFN_VALID > /* We might have to check for holes inside the memmap. */ > if (!pfn_valid()) > return NULL; > #endif
I have to confess that I was a bit confused by pfn_valid_within + HOLES_IN_ZONES + HAVE_ARCH_PFN_VALID. At first I thought that we should stick with pfn_valid_within, as we also depend on HOLES_IN_ZONES, so it could be that if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID)) ... would to too much work, as if CONFIG_HOLES_IN_ZONES was not set but an arch pfn_valid was provided, we would perform unedeed checks. But on a closer look, CONFIG_HOLES_IN_ZONES is set by default on arm64, and on ia64 when SPARSEMEM is set, so looks fine. -- Oscar Salvador SUSE L3
