Vishal Verma wrote: > The MHP_MEMMAP_ON_MEMORY flag for hotplugged memory is restricted to > 'memblock_size' chunks of memory being added. Adding a larger span of > memory precludes memmap_on_memory semantics. > > For users of hotplug such as kmem, large amounts of memory might get > added from the CXL subsystem. In some cases, this amount may exceed the > available 'main memory' to store the memmap for the memory being added. > In this case, it is useful to have a way to place the memmap on the > memory being added, even if it means splitting the addition into > memblock-sized chunks. > > Change add_memory_resource() to loop over memblock-sized chunks of > memory if caller requested memmap_on_memory, and if other conditions for > it are met. Teach try_remove_memory() to also expect that a memory > range being removed might have been split up into memblock sized chunks, > and to loop through those as needed. > > Cc: Andrew Morton <[email protected]> > Cc: David Hildenbrand <[email protected]> > Cc: Michal Hocko <[email protected]> > Cc: Oscar Salvador <[email protected]> > Cc: Dan Williams <[email protected]> > Cc: Dave Jiang <[email protected]> > Cc: Dave Hansen <[email protected]> > Cc: Huang Ying <[email protected]> > Suggested-by: David Hildenbrand <[email protected]> > Signed-off-by: Vishal Verma <[email protected]> > --- > mm/memory_hotplug.c | 162 > ++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 99 insertions(+), 63 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index f8d3e7427e32..77ec6f15f943 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1380,6 +1380,44 @@ static bool mhp_supports_memmap_on_memory(unsigned > long size) > return arch_supports_memmap_on_memory(vmemmap_size); > } > > +static int add_memory_create_devices(int nid, struct memory_group *group, > + u64 start, u64 size, mhp_t mhp_flags) > +{ > + struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) }; > + struct vmem_altmap mhp_altmap = { > + .base_pfn = PHYS_PFN(start), > + .end_pfn = PHYS_PFN(start + size - 1), > + }; > + int ret; > + > + if ((mhp_flags & MHP_MEMMAP_ON_MEMORY)) { > + mhp_altmap.free = memory_block_memmap_on_memory_pages(); > + params.altmap = kmalloc(sizeof(struct vmem_altmap), GFP_KERNEL); > + if (!params.altmap) > + return -ENOMEM; > + > + memcpy(params.altmap, &mhp_altmap, sizeof(mhp_altmap));
Isn't this just open coded kmemdup()? Other than that, I am not seeing anything else to comment on, you can add: Reviewed-by: Dan Williams <[email protected]>
