[PATCH v4 1/2] kho: fix deferred init of kho scratch

[Michal Clapinski]

Currently, mm_core_init calls kho_memory_init, which calls
kho_release_scratch.

If DEFERRED is enabled, kho_release_scratch will first initialize the
struct pages of kho scratch. This is not needed. We can just let
page_alloc_init_late init it.

Next, kho_release_scratch will mark scratch as MIGRATE_CMA. If DEFERRED
is enabled, this will be overwritten later in deferred_free_pages.

To fix this, I removed the whole kho_release_scratch.
Marking the pageblocks as MIGRATE_CMA now happens in kho_init, which
runs after deferred_free_pages.

Signed-off-by: Michal Clapinski <mclapinski@xxxxxxxxxx>
---
 include/linux/memblock.h           |  2 --
 kernel/liveupdate/kexec_handover.c | 43 ++++++++----------------------
 mm/memblock.c                      | 22 ---------------
 3 files changed, 11 insertions(+), 56 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 221118b5a16e..35d9cf6bbf7a 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 b851b09a8e99..de167bfa2c8d 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -1377,11 +1377,6 @@ static __init int kho_init(void)
 	if (err)
 		goto err_free_fdt;
 
-	if (fdt) {
-		kho_in_debugfs_init(&kho_in.dbg, fdt);
-		return 0;
-	}
-
 	for (int i = 0; i < kho_scratch_cnt; i++) {
 		unsigned long base_pfn = PHYS_PFN(kho_scratch[i].addr);
 		unsigned long count = kho_scratch[i].size >> PAGE_SHIFT;
@@ -1397,8 +1392,17 @@ static __init int kho_init(void)
 		 */
 		kmemleak_ignore_phys(kho_scratch[i].addr);
 		for (pfn = base_pfn; pfn < base_pfn + count;
-		     pfn += pageblock_nr_pages)
-			init_cma_reserved_pageblock(pfn_to_page(pfn));
+		     pfn += pageblock_nr_pages) {
+			if (fdt)
+				init_cma_pageblock(pfn_to_page(pfn));
+			else
+				init_cma_reserved_pageblock(pfn_to_page(pfn));
+		}
+	}
+
+	if (fdt) {
+		kho_in_debugfs_init(&kho_in.dbg, fdt);
+		return 0;
 	}
 
 	WARN_ON_ONCE(kho_debugfs_fdt_add(&kho_out.dbg, "fdt",
@@ -1421,35 +1425,10 @@ static __init int kho_init(void)
 }
 fs_initcall(kho_init);
 
-static void __init kho_release_scratch(void)
-{
-	phys_addr_t start, end;
-	u64 i;
-
-	memmap_init_kho_scratch_pages();
-
-	/*
-	 * Mark scratch mem as CMA before we return it. That way we
-	 * ensure that no kernel allocations happen on it. That means
-	 * 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) {
-		ulong start_pfn = pageblock_start_pfn(PFN_DOWN(start));
-		ulong end_pfn = pageblock_align(PFN_UP(end));
-		ulong pfn;
-
-		for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages)
-			init_pageblock_migratetype(pfn_to_page(pfn),
-						   MIGRATE_CMA, false);
-	}
-}
-
 void __init kho_memory_init(void)
 {
 	if (kho_in.mem_map_phys) {
 		kho_scratch = phys_to_virt(kho_in.scratch_phys);
-		kho_release_scratch();
 		kho_mem_deserialize(phys_to_virt(kho_in.mem_map_phys));
 	} else {
 		kho_reserve_scratch();
diff --git a/mm/memblock.c b/mm/memblock.c
index 6cff515d82f4..3eff19124fc0 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
 
 /**
-- 
2.53.0.345.g96ddfc5eaa-goog