diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2791f568bdb2..3e4fb430ae45 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -192,6 +192,9 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)
 	return MM_FAULT_CONTINUE;
 }
 
+// This comes from 64-bit struct rt_sigframe + __SIGNAL_FRAMESIZE
+#define SIGFRAME_MAX_SIZE	(4096 + 128)
+
 /*
  * For 600- and 800-family processors, the error_code parameter is DSISR
  * for a data fault, SRR1 for an instruction fault. For 400-family processors
@@ -341,7 +344,7 @@ retry:
 	/*
 	 * N.B. The POWER/Open ABI allows programs to access up to
 	 * 288 bytes below the stack pointer.
-	 * The kernel signal delivery code writes up to about 1.5kB
+	 * The kernel signal delivery code writes up to about 4kB
 	 * below the stack pointer (r1) before decrementing it.
 	 * The exec code can write slightly over 640kB to the stack
 	 * before setting the user r1.  Thus we allow the stack to
@@ -365,7 +368,7 @@ retry:
 		 * between the last mapped region and the stack will
 		 * expand the stack rather than segfaulting.
 		 */
-		if (address + 2048 < uregs->gpr[1] && !store_update_sp)
+		if (address + SIGFRAME_MAX_SIZE < uregs->gpr[1] && !store_update_sp)
 			goto bad_area;
 	}
 	if (expand_stack(vma, address))