powerpc/mm/altmap: Fix altmap boundary check

kvaneesh · mpe · commit 6722b2571205 · 2023-07-28T16:47:19.000+10:00
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: 9ef3463 ("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
@@ -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);

Original file line number	Diff line number	Diff line change
`@@ -314,8 +314,7 @@ void __ref vmemmap_free(unsigned long start, unsigned long end,`
`314`	`314`	`start = ALIGN_DOWN(start, page_size);`
`315`	`315`	`if (altmap) {`
`316`	`316`	`alt_start = altmap->base_pfn;`
`317`		`- alt_end = altmap->base_pfn + altmap->reserve +`
`318`		`- altmap->free + altmap->alloc + altmap->align;`
	`317`	`+ alt_end = altmap->base_pfn + altmap->reserve + altmap->free;`
`319`	`318`	`}`
`320`	`319`
`321`	`320`	`pr_debug("vmemmap_free %lx...%lx\n", start, end);`