diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index f5bd046f9e194183532eca3e87d6e07e60a57a6b..5023c7e1f7540f153d32f8d107be79939f45df67 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -63,8 +63,34 @@ EXPORT_SYMBOL(memstart_addr);
  * unless restricted on specific platforms (e.g. 30-bit on Raspberry Pi 4).
  * In such case, ZONE_DMA32 covers the rest of the 32-bit addressable memory,
  * otherwise it is empty.
+ *
+ * Memory reservation for crash kernel either done early or deferred
+ * depending on DMA memory zones configs (ZONE_DMA) --
+ *
+ * In absence of ZONE_DMA configs arm64_dma_phys_limit initialized
+ * here instead of max_zone_phys().  This lets early reservation of
+ * crash kernel memory which has a dependency on arm64_dma_phys_limit.
+ * Reserving memory early for crash kernel allows linear creation of block
+ * mappings (greater than page-granularity) for all the memory bank rangs.
+ * In this scheme a comparatively quicker boot is observed.
+ *
+ * If ZONE_DMA configs are defined, crash kernel memory reservation
+ * is delayed until DMA zone memory range size initilazation performed in
+ * zone_sizes_init().  The defer is necessary to steer clear of DMA zone
+ * memory range to avoid overlap allocation.  So crash kernel memory boundaries
+ * are not known when mapping all bank memory ranges, which otherwise means
+ * not possible to exclude crash kernel range from creating block mappings
+ * so page-granularity mappings are created for the entire memory range.
+ * Hence a slightly slower boot is observed.
+ *
+ * Note: Page-granularity mapppings are necessary for crash kernel memory
+ * range for shrinking its size via /sys/kernel/kexec_crash_size interface.
  */
-phys_addr_t arm64_dma_phys_limit __ro_after_init;
+#if IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)
+phys_addr_t __ro_after_init arm64_dma_phys_limit;
+#else
+phys_addr_t __ro_after_init arm64_dma_phys_limit = PHYS_MASK + 1;
+#endif
 
 #ifndef CONFIG_KEXEC_CORE
 static void __init reserve_crashkernel(void)
@@ -173,8 +199,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 	if (!arm64_dma_phys_limit)
 		arm64_dma_phys_limit = dma32_phys_limit;
 #endif
-	if (!arm64_dma_phys_limit)
-		arm64_dma_phys_limit = PHYS_MASK + 1;
 	max_zone_pfns[ZONE_NORMAL] = max;
 
 	free_area_init(max_zone_pfns);
@@ -498,6 +522,9 @@ void __init arm64_memblock_init(void)
 
 	reserve_elfcorehdr();
 
+	if (!IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32))
+		reserve_crashkernel();
+
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 }
 
@@ -553,7 +580,8 @@ void __init bootmem_init(void)
 	 * request_standard_resources() depends on crashkernel's memory being
 	 * reserved, so do it here.
 	 */
-	reserve_crashkernel();
+	if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32))
+		reserve_crashkernel();
 
 	reserve_quick_kexec();
 
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 00e89be15ad2584375b3f583d36b70615a61f554..e767653540407334bc782a5331578933297ca8ad 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -562,16 +562,6 @@ static void __init map_mem(pgd_t *pgdp)
 		       PAGE_KERNEL, NO_CONT_MAPPINGS);
 	memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
 
-#ifdef CONFIG_KEXEC_CORE
-	if (crashk_res.end) {
-		__map_memblock(pgdp, crashk_res.start,
-			       crashk_res.end + 1,
-			       PAGE_KERNEL,
-			       NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
-		memblock_clear_nomap(crashk_res.start,
-				     resource_size(&crashk_res));
-	}
-#endif
 #ifdef CONFIG_KFENCE
 	/*
 	 * Map the __kfence_pool at page granularity now.
@@ -584,6 +574,22 @@ static void __init map_mem(pgd_t *pgdp)
 		memblock_clear_nomap(__pa(__kfence_pool), KFENCE_POOL_SIZE);
 	}
 #endif
+
+	/*
+	 * Use page-level mappings here so that we can shrink the region
+	 * in page granularity and put back unused memory to buddy system
+	 * through /sys/kernel/kexec_crash_size interface.
+	 */
+#ifdef CONFIG_KEXEC_CORE
+	if (crashk_res.end) {
+		__map_memblock(pgdp, crashk_res.start,
+			       crashk_res.end + 1,
+			       PAGE_KERNEL,
+			       NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
+		memblock_clear_nomap(crashk_res.start,
+				     resource_size(&crashk_res));
+	}
+#endif
 }
 
 void mark_rodata_ro(void)