Merge: Updates for radix vmemmap

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7103

Description: Updates for radix vmemmap

JIRA: https://issues.redhat.com/browse/RHEL-99806

Build Info: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=68185751

Tested: Verified Brew build test kernel RPMs

Signed-off-by: Mamatha Inamdar <minamdar@redhat.com>

Approved-by: Steve Best <sbest@redhat.com>
Approved-by: Waiman Long <longman@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Approved-by: Rafael Aquini <raquini@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

arch/powerpc/mm/book3s64/radix_pgtable.c

@@ -1003,14 +1003,15 @@ int __meminit radix__vmemmap_create_mapping(unsigned long start,
 	return 0;
 }
 
-
+#ifdef CONFIG_ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
 bool vmemmap_can_optimize(struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
 {
 	if (radix_enabled())
 		return __vmemmap_can_optimize(altmap, pgmap);
 
 	return false;
 }
+#endif
 
 int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
 				unsigned long addr, unsigned long next)
@@ -1147,6 +1148,19 @@ int __meminit radix__vmemmap_populate(unsigned long start, unsigned long end, in
 	pmd_t *pmd;
 	pte_t *pte;
 
+	/*
+	 * Make sure we align the start vmemmap addr so that we calculate
+	 * the correct start_pfn in altmap boundary check to decided whether
+	 * we should use altmap or RAM based backing memory allocation. Also
+	 * the address need to be aligned for set_pte operation.
+
+	 * If the start addr is already PMD_SIZE aligned we will try to use
+	 * a pmd mapping. We don't want to be too aggressive here beacause
+	 * that will cause more allocations in RAM. So only if the namespace
+	 * vmemmap start addr is PMD_SIZE aligned we will use PMD mapping.
+	 */
+
+	start = ALIGN_DOWN(start, PAGE_SIZE);
 	for (addr = start; addr < end; addr = next) {
 		next = pmd_addr_end(addr, end);
 
@@ -1172,8 +1186,8 @@ int __meminit radix__vmemmap_populate(unsigned long start, unsigned long end, in
 			 * in altmap block allocation failures, in which case
 			 * we fallback to RAM for vmemmap allocation.
 			 */
-			if (altmap && (!IS_ALIGNED(addr, PMD_SIZE) ||
-				       altmap_cross_boundary(altmap, addr, PMD_SIZE))) {
+			if (!IS_ALIGNED(addr, PMD_SIZE) || (altmap &&
+			    altmap_cross_boundary(altmap, addr, PMD_SIZE))) {
 				/*
 				 * make sure we don't create altmap mappings
 				 * covering things outside the device.