powerpc/fadump: Account for memory_limit while reserving memory

If the memory chunk found for reserving memory overshoots the memory
limit imposed, do not proceed with reserving memory. Default behavior
was this until commit 140777a3 ("powerpc/fadump: consider reserved
ranges while reserving memory") changed it unwittingly.

Fixes: 140777a3 ("powerpc/fadump: consider reserved ranges while reserving memory")
Cc: stable@vger.kernel.org
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159057266320.22331.6571453892066907320.stgit@hbathini.in.ibm.com

arch/powerpc/kernel/fadump.c

@@ -603,7 +603,7 @@ int __init fadump_reserve_mem(void)
 		 */
 		base = fadump_locate_reserve_mem(base, size);
 
-		if (!base) {
+		if (!base || (base + size > mem_boundary)) {
 			pr_err("Failed to find memory chunk for reservation!\n");
 			goto error_out;
 		}