Hi, Dan, Dan Williams <dan.j.williams@xxxxxxxxx> writes: > David Hildenbrand wrote: >> On 15.10.24 10:03, Huang, Ying wrote: >> > Hi, David, >> > >> > David Hildenbrand <david@xxxxxxxxxx> writes: >> > >> >> On 15.10.24 07:15, Huang Ying wrote: >> >>> We want to use the functions configured via GET_FREE_REGION in >> >>> resource kunit tests. However, GET_FREE_REGION depends on SPARSEMEM. >> >>> This makes resource kunit tests cannot be built on some architectures >> >>> lacking SPARSEMEM. In fact, these functions doesn't depend on >> >>> SPARSEMEM now. So, remove dependency on SPARSEMEM from >> >>> GET_FREE_REGION. >> >>> Link: >> >>> https://lore.kernel.org/lkml/20240922225041.603186-1-linux@xxxxxxxxxxxx/ >> >>> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> >> >>> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx> >> >>> Cc: Nathan Chancellor <nathan@xxxxxxxxxx> >> >>> Cc: Arnd Bergmann <arnd@xxxxxxxx> >> >>> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> >> >>> Cc: David Hildenbrand <david@xxxxxxxxxx> >> >>> Cc: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx> >> >>> --- >> >>> mm/Kconfig | 1 - >> >>> 1 file changed, 1 deletion(-) >> >>> diff --git a/mm/Kconfig b/mm/Kconfig >> >>> index 4c9f5ea13271..33fa51d608dc 100644 >> >>> --- a/mm/Kconfig >> >>> +++ b/mm/Kconfig >> >>> @@ -1085,7 +1085,6 @@ config HMM_MIRROR >> >>> depends on MMU >> >>> config GET_FREE_REGION >> >>> - depends on SPARSEMEM >> >>> bool >> >>> config DEVICE_PRIVATE >> >> >> >> Added by >> >> >> >> commit 14b80582c43e4f550acfd93c2b2cadbe36ea0874 >> >> Author: Dan Williams <dan.j.williams@xxxxxxxxx> >> >> Date: Fri May 20 13:41:24 2022 -0700 >> >> >> >> resource: Introduce alloc_free_mem_region() >> >> >> >> @Dan, any insight why that dependency was added? >> > >> > Dan has explain it some what in the following email, >> > >> > https://lore.kernel.org/lkml/66f5abd431dce_964f2294b9@xxxxxxxxxxxxxxxxxxxxxxxxx.notmuch/ >> > >> > This is reachable from the "Link:" tag in the patch. >> >> That should be part of the patch description then :) > > That Link: does not really describe the history though... Sorry. I made a mistake here. > The description I would add is: > > --- > > When get_free_mem_region() was introduced the only consumers were those > looking to pass the address range to memremap_pages(). That address > range needed to be mindful of the maximum addressable platform physical > address which at the time only SPARSMEM defined via MAX_PHYSMEM_BITS. > > Given that memremap_pages() also depended on SPARSEMEM via ZONE_DEVICE, > it was easier to just depend on that definition than invent a general > MAX_PHYSMEM_BITS concept outside of SPARSEMEM. > > Turns out that decision was buggy and did not account for KASAN > consumption of physical address space. That problem was resolved > recently with commit ea72ce5da228 ("x86/kaslr: Expose and use the end of > the physical memory address space"), and GET_FREE_REGION dropped its > MAX_PHYSMEM_BITS dependency. > > Then commit 99185c10d5d9 ("resource, kunit: add test case for > region_intersects()"), went ahead and fixed up the only remaining > dependency on SPARSEMEM which was usage of the PA_SECTION_SHIFT macro > for setting the default alignment. A PAGE_SIZE fallback is fine in the > SPARSEMEM=n case. > > With those build dependencies gone GET_FREE_REGION no longer depends on > SPARSEMEM. This looks great! Will use this in the patch description in the next version. -- Best Regards, Huang, Ying
