powerpc/mm/altmap: Fix altmap boundary check

[ Upstream commit 6722b25712054c0f903b839b8f5088438dd04df3 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index b76cd49d521b9d45dfa442c142e10648ea69b313..db040f34c0046f12cca54799016270d5282a3a3c 100644 (file)
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -313,8 +313,7 @@ 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);