aarch64: increase DEFAULT_CRASH_KERNEL_LOW_SIZE for kdump

Increase minimum lowmem reservation for crashkernel to 256M for aarch64.
Without this fix we hit allocation failures in kdump environment when
loading modules and when dumping vmcore over NFS.

Orabug: 37446372
Signed-off-by: Brian Maly <[email protected]>
Reviewed-by: Jack Vogel <[email protected]>

Author: Brian Maly

include/linux/crash_reserve.h

@@ -20,8 +20,12 @@ int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 
 #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
 #ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
+#ifdef __aarch64__
+#define DEFAULT_CRASH_KERNEL_LOW_SIZE   (256UL << 20)
+#else
 #define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
 #endif
+#endif
 #ifndef CRASH_ALIGN
 #define CRASH_ALIGN			SZ_2M
 #endif