On 17.12.20 16:28, 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 > ensure that the range has been validated with memhp_range_allowed() earlier > in the call chain. Besides memhp_get_pluggable_range() also can be used by > potential memory hotplug callers to avail the allowed physical range which > would go through on a given platform. > > This does not really add any new range check in generic memory hotplug but > instead compensates for lost checks in arch_add_memory() where applicable > and check_hotplug_memory_addressable(), with unified memhp_range_allowed(). > Subject s/mm\/hotplug/mm\/memory_hotplug/ Everywhere in this patch: Use "true/false" for boolean values. > Cc: David Hildenbrand <david@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Suggested-by: David Hildenbrand <david@xxxxxxxxxx> > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> > --- > include/linux/memory_hotplug.h | 10 +++++ > mm/memory_hotplug.c | 79 +++++++++++++++++++++++++--------- > mm/memremap.c | 6 +++ > 3 files changed, 75 insertions(+), 20 deletions(-) > > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index 551093b74596..8d72354758c8 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -70,6 +70,9 @@ typedef int __bitwise mhp_t; > */ > #define MEMHP_MERGE_RESOURCE ((__force mhp_t)BIT(0)) > > +bool memhp_range_allowed(u64 start, u64 size, bool need_mapping); > +struct range memhp_get_pluggable_range(bool need_mapping); AFAIKs, all memhp_get_pluggable_range() users pass "1". What about the "add_pages()-only" path? -- Thanks, David / dhildenb
