[PATCH v7 2/3] kho: fix deferred init of kho scratch

[Michal Clapinski]

Currently, if DEFERRED is enabled, kho_release_scratch will initialize
the struct pages and set migratetype of kho scratch. Unless the whole
scratch fit below first_deferred_pfn, some of that will be overwritten
either by deferred_init_pages or memmap_init_reserved_pages.

To fix it, I modified kho_release_scratch to only set the migratetype
on already initialized pages. Then, modified init_pageblock_migratetype
to set the migratetype to CMA if the page is located inside scratch.

Signed-off-by: Michal Clapinski <mclapinski at google.com>
---
 include/linux/memblock.h           |  2 --
 kernel/liveupdate/kexec_handover.c | 10 ++++++----
 mm/memblock.c                      | 22 ----------------------
 mm/page_alloc.c                    |  7 +++++++
 4 files changed, 13 insertions(+), 28 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 6ec5e9ac0699..3e217414e12d 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -614,11 +614,9 @@ static inline void memtest_report_meminfo(struct seq_file *m) { }
 #ifdef CONFIG_MEMBLOCK_KHO_SCRATCH
 void memblock_set_kho_scratch_only(void);
 void memblock_clear_kho_scratch_only(void);
-void memmap_init_kho_scratch_pages(void);
 #else
 static inline void memblock_set_kho_scratch_only(void) { }
 static inline void memblock_clear_kho_scratch_only(void) { }
-static inline void memmap_init_kho_scratch_pages(void) {}
 #endif
 
 #endif /* _LINUX_MEMBLOCK_H */
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index c9b982372d6e..e511a50fab9c 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -1477,8 +1477,7 @@ static void __init kho_release_scratch(void)
 {
 	phys_addr_t start, end;
 	u64 i;
-
-	memmap_init_kho_scratch_pages();
+	int nid;
 
 	/*
 	 * Mark scratch mem as CMA before we return it. That way we
@@ -1486,10 +1485,13 @@ static void __init kho_release_scratch(void)
 	 * we can reuse it as scratch memory again later.
 	 */
 	__for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
-			     MEMBLOCK_KHO_SCRATCH, &start, &end, NULL) {
+			     MEMBLOCK_KHO_SCRATCH, &start, &end, &nid) {
 		ulong start_pfn = pageblock_start_pfn(PFN_DOWN(start));
 		ulong end_pfn = pageblock_align(PFN_UP(end));
 		ulong pfn;
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+		end_pfn = min(end_pfn, NODE_DATA(nid)->first_deferred_pfn);
+#endif
 
 		for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages)
 			init_pageblock_migratetype(pfn_to_page(pfn),
@@ -1500,8 +1502,8 @@ static void __init kho_release_scratch(void)
 void __init kho_memory_init(void)
 {
 	if (kho_in.scratch_phys) {
-		kho_scratch = phys_to_virt(kho_in.scratch_phys);
 		kho_release_scratch();
+		kho_scratch = phys_to_virt(kho_in.scratch_phys);
 
 		if (kho_mem_retrieve(kho_get_fdt()))
 			kho_in.fdt_phys = 0;
diff --git a/mm/memblock.c b/mm/memblock.c
index b3ddfdec7a80..ae6a5af46bd7 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -959,28 +959,6 @@ __init void memblock_clear_kho_scratch_only(void)
 {
 	kho_scratch_only = false;
 }
-
-__init void memmap_init_kho_scratch_pages(void)
-{
-	phys_addr_t start, end;
-	unsigned long pfn;
-	int nid;
-	u64 i;
-
-	if (!IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT))
-		return;
-
-	/*
-	 * Initialize struct pages for free scratch memory.
-	 * The struct pages for reserved scratch memory will be set up in
-	 * reserve_bootmem_region()
-	 */
-	__for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
-			     MEMBLOCK_KHO_SCRATCH, &start, &end, &nid) {
-		for (pfn = PFN_UP(start); pfn < PFN_DOWN(end); pfn++)
-			init_deferred_page(pfn, nid);
-	}
-}
 #endif
 
 /**
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ee81f5c67c18..5ca078dde61d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -55,6 +55,7 @@
 #include <linux/cacheinfo.h>
 #include <linux/pgalloc_tag.h>
 #include <linux/mmzone_lock.h>
+#include <linux/kexec_handover.h>
 #include <asm/div64.h>
 #include "internal.h"
 #include "shuffle.h"
@@ -549,6 +550,12 @@ void __meminit init_pageblock_migratetype(struct page *page,
 		     migratetype < MIGRATE_PCPTYPES))
 		migratetype = MIGRATE_UNMOVABLE;
 
+	/*
+	 * Mark KHO scratch as CMA so no unmovable allocations are made there.
+	 */
+	if (unlikely(kho_scratch_overlap(page_to_phys(page), PAGE_SIZE)))
+		migratetype = MIGRATE_CMA;
+
 	flags = migratetype;
 
 #ifdef CONFIG_MEMORY_ISOLATION
-- 
2.53.0.851.ga537e3e6e9-goog