On Wed, Jan 20, 2021 at 11:41:53AM +0100, David Hildenbrand wrote: > On 20.01.21 09:33, Anshuman Khandual wrote: > > > > > > On 1/19/21 5:51 PM, David Hildenbrand wrote: > >> On 18.01.21 14:12, Anshuman Khandual wrote: > >>> This introduces memhp_range_allowed() which can be called in various memory > >>> hotplug paths to prevalidate the address range which is being added, with > >>> the platform. Then memhp_range_allowed() calls memhp_get_pluggable_range() > >>> which provides applicable address range depending on whether linear mapping > >>> is required or not. For ranges that require linear mapping, it calls a new > >>> arch callback arch_get_mappable_range() which the platform can override. So > >>> the new callback, in turn provides the platform an opportunity to configure > >>> acceptable memory hotplug address ranges in case there are constraints. > >>> > >>> This mechanism will help prevent platform specific errors deep down during > >>> hotplug calls. This drops now redundant check_hotplug_memory_addressable() > >>> check in __add_pages() but instead adds a VM_BUG_ON() check which would > >> > >> In this patch, you keep the __add_pages() checks. But as discussed, we > >> could perform it in mm/memremap.c:pagemap_range() insted and convert it > >> to a VM_BUG_ON(). > > > > Just to be sure, will the following change achieve what you are > > suggesting here. pagemap_range() after this change, will again > > be the same like the V1 series. > > Yeah, as we used to have in v1. Maybe other reviewers (@Oscar?) have a > different opinion. No, I think that placing the check in pagemap_range() out of the if-else makes much more sense. Actually, unless my memory fails me that is what I suggested in v2. I plan to have a look at the series later this week as I am fairly busy atm. Thanks -- Oscar Salvador SUSE L3
