[PATCH 6.1 115/127] powerpc/mm/altmap: Fix altmap boundary check

Greg Kroah-Hartman
2023-08-09T10:56:31Z

From: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

[ 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>
---
arch/powerpc/mm/init_64.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index fe1b83020e0df..0ec5b45b1e86a 100644
--- 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);
--
2.40.1