--- a/hotspot/src/os/aix/vm/os_aix.cpp	Mon Nov 16 18:50:55 2015 -0500
+++ b/hotspot/src/os/aix/vm/os_aix.cpp	Thu Nov 05 15:05:59 2015 +0100
@@ -2769,8 +2769,12 @@
   // Get signal number to use for suspend/resume
   if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
     int sig = ::strtol(s, 0, 10);
-    if (sig > 0 || sig < NSIG) {
+    if (sig > MAX2(SIGSEGV, SIGBUS) &&  // See 4355769.
+        sig < NSIG) {                   // Must be legal signal and fit into sigflags[].
       SR_signum = sig;
+    } else {
+      warning("You set _JAVA_SR_SIGNUM=%d. It must be in range [%d, %d]. Using %d instead.",
+              sig, MAX2(SIGSEGV, SIGBUS)+1, NSIG-1, SR_signum);
     }
   }
 
@@ -2966,8 +2970,8 @@
 bool os::Aix::signal_handlers_are_installed = false;
 
 // For signal-chaining
-struct sigaction os::Aix::sigact[MAXSIGNUM];
-unsigned int os::Aix::sigs = 0;
+struct sigaction sigact[NSIG];
+sigset_t sigs;
 bool os::Aix::libjsig_is_loaded = false;
 typedef struct sigaction *(*get_signal_t)(int);
 get_signal_t os::Aix::get_signal_action = NULL;
@@ -3045,29 +3049,31 @@
 }
 
 struct sigaction* os::Aix::get_preinstalled_handler(int sig) {
-  if ((((unsigned int)1 << sig) & sigs) != 0) {
+  if (sigismember(&sigs, sig)) {
     return &sigact[sig];
   }
   return NULL;
 }
 
 void os::Aix::save_preinstalled_handler(int sig, struct sigaction& oldAct) {
-  assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
+  assert(sig > 0 && sig < NSIG, "vm signal out of expected range");
   sigact[sig] = oldAct;
-  sigs |= (unsigned int)1 << sig;
+  sigaddset(&sigs, sig);
 }
 
 // for diagnostic
-int os::Aix::sigflags[MAXSIGNUM];
+int sigflags[NSIG];
 
 int os::Aix::get_our_sigflags(int sig) {
-  assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
+  assert(sig > 0 && sig < NSIG, "vm signal out of expected range");
   return sigflags[sig];
 }
 
 void os::Aix::set_our_sigflags(int sig, int flags) {
-  assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
-  sigflags[sig] = flags;
+  assert(sig > 0 && sig < NSIG, "vm signal out of expected range");
+  if (sig > 0 && sig < NSIG) {
+    sigflags[sig] = flags;
+  }
 }
 
 void os::Aix::set_signal_handler(int sig, bool set_installed) {
@@ -3107,7 +3113,7 @@
     sigAct.sa_flags = SA_SIGINFO|SA_RESTART;
   }
   // Save flags, which are set by ours
-  assert(sig > 0 && sig < MAXSIGNUM, "vm signal out of expected range");
+  assert(sig > 0 && sig < NSIG, "vm signal out of expected range");
   sigflags[sig] = sigAct.sa_flags;
 
   int ret = sigaction(sig, &sigAct, &oldAct);
@@ -3140,10 +3146,11 @@
       assert(UseSignalChaining, "should enable signal-chaining");
     }
     if (libjsig_is_loaded) {
-      // Tell libjsig jvm is setting signal handlers
+      // Tell libjsig jvm is setting signal handlers.
       (*begin_signal_setting)();
     }
 
+    ::sigemptyset(&sigs);
     set_signal_handler(SIGSEGV, true);
     set_signal_handler(SIGPIPE, true);
     set_signal_handler(SIGBUS, true);