diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 55d6ede30c19..9ab344d29a54 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -136,6 +136,7 @@ int load_crashdump_segments_ppc64(struct kimage *image,
 int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
 			  const void *fdt, unsigned long kernel_load_addr,
 			  unsigned long fdt_load_addr);
+unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image);
 int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
 			unsigned long initrd_load_addr,
 			unsigned long initrd_len, const char *cmdline);
diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index d0e459bb2f05..9842e33533df 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -102,7 +102,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 		pr_debug("Loaded initrd at 0x%lx\n", initrd_load_addr);
 	}
 
-	fdt_size = fdt_totalsize(initial_boot_params) * 2;
+	fdt_size = kexec_fdt_totalsize_ppc64(image);
 	fdt = kmalloc(fdt_size, GFP_KERNEL);
 	if (!fdt) {
 		pr_err("Not enough memory for the device tree.\n");
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index c69bcf9b547a..02b9e4d0dc40 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -21,6 +21,7 @@
 #include <linux/memblock.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <asm/setup.h>
 #include <asm/drmem.h>
 #include <asm/kexec_ranges.h>
 #include <asm/crashdump-ppc64.h>
@@ -925,6 +926,40 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
 	return ret;
 }
 
+/**
+ * kexec_fdt_totalsize_ppc64 - Return the estimated size needed to setup FDT
+ *                             for kexec/kdump kernel.
+ * @image:                     kexec image being loaded.
+ *
+ * Returns the estimated size needed for kexec/kdump kernel FDT.
+ */
+unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
+{
+	unsigned int fdt_size;
+	u64 usm_entries;
+
+	/*
+	 * The below estimate more than accounts for a typical kexec case where
+	 * the additional space is to accommodate things like kexec cmdline,
+	 * chosen node with properties for initrd start & end addresses and
+	 * a property to indicate kexec boot..
+	 */
+	fdt_size = fdt_totalsize(initial_boot_params) + (2 * COMMAND_LINE_SIZE);
+	if (image->type != KEXEC_TYPE_CRASH)
+		return fdt_size;
+
+	/*
+	 * For kdump kernel, also account for linux,usable-memory and
+	 * linux,drconf-usable-memory properties. Get an approximate on the
+	 * number of usable memory entries and use for FDT size estimation.
+	 */
+	usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) +
+		       (2 * (resource_size(&crashk_res) / drmem_lmb_size())));
+	fdt_size += (unsigned int)(usm_entries * sizeof(u64));
+
+	return fdt_size;
+}
+
 /**
  * setup_new_fdt_ppc64 - Update the flattend device-tree of the kernel
  *                       being loaded.