powerpc/mm/altmap: Fix altmap boundary check

altmap->free includes the entire free space from which altmap blocks
can be allocated. So when checking whether the kernel is doing altmap
block free, compute the boundary correctly, otherwise memory hotunplug
can fail.

Fixes: 9ef34630a461 ("powerpc/mm: Fallback to RAM if the altmap is unusable")
Signed-off-by: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230724181320.471386-1-aneesh.kumar@linux.ibm.com

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index fe1b83020e0df0c700eae0a816d5257c1059cc76..0ec5b45b1e86adc771bf85da57e3622a75b721e4 100644 (file)
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -314,8 +314,7 @@ void __ref vmemmap_free(unsigned long start, unsigned long end,
        start = ALIGN_DOWN(start, page_size);
        if (altmap) {
                alt_start = altmap->base_pfn;
-               alt_end = altmap->base_pfn + altmap->reserve +
-                         altmap->free + altmap->alloc + altmap->align;
+               alt_end = altmap->base_pfn + altmap->reserve + altmap->free;
        }
 
        pr_debug("vmemmap_free %lx...%lx\n", start, end);