vm->exiting: deal with exit_group() and concurrent page faults

kernel/include/process.h

@@ -431,6 +431,7 @@ struct process_vm {
 
 	cpu_set_t cpu_set;
 	ihk_spinlock_t cpu_set_lock;
+	int exiting;
 };
 
 

kernel/mem.c

@@ -370,10 +370,25 @@ static void page_fault_handler(void *fault_addr, uint64_t reason, void *regs)
 	dkprintf("[%d]page_fault_handler(%p,%lx,%p)\n",
 			ihk_mc_get_processor_id(), fault_addr, reason, regs);
 
+	cpu_enable_interrupt();
+
 	error = page_fault_process_vm(proc->vm, fault_addr, reason);
 	if (error) {
 		struct siginfo info;
 
+		if (error == -ECANCELED) {
+			kprintf("process is exiting, terminate.\n");
+
+			ihk_mc_spinlock_lock_noirq(&proc->ftn->lock);
+			proc->ftn->status = PS_ZOMBIE;
+			ihk_mc_spinlock_unlock_noirq(&proc->ftn->lock);	
+			release_fork_tree_node(proc->ftn->parent);
+			release_fork_tree_node(proc->ftn);
+			//release_process(proc);
+
+			schedule();
+		}
+
 		kprintf("[%d]page_fault_handler(%p,%lx,%p):"
 				"fault vm failed. %d\n",
 				ihk_mc_get_processor_id(), fault_addr,

kernel/process.c

@@ -137,6 +137,7 @@ static int init_process_vm(struct process *owner, struct process_vm *vm)
 	vm->owner_process = owner;
 	memset(&vm->cpu_set, 0, sizeof(cpu_set_t));
 	ihk_mc_spinlock_init(&vm->cpu_set_lock);
+	vm->exiting = 0;
 
 	return 0;
 }
@@ -1526,6 +1527,11 @@ static int do_page_fault_process_vm(struct process_vm *vm, void *fault_addr0, ui
 
 	ihk_mc_spinlock_lock_noirq(&vm->memory_range_lock);
 
+	if (vm->exiting) {
+		error = -ECANCELED;
+		goto out;
+	}
+
 	range = lookup_process_memory_range(vm, fault_addr, fault_addr+1);
 	if (range == NULL) {
 		error = -EFAULT;
@@ -1854,6 +1860,8 @@ void flush_process_memory(struct process *proc)
 
 	dkprintf("flush_process_memory(%p)\n", proc);
 	ihk_mc_spinlock_lock_noirq(&vm->memory_range_lock);
+	/* Let concurrent page faults know the VM will be gone */
+	vm->exiting = 1;
 	list_for_each_entry_safe(range, next, &vm->vm_range_list, list) {
 		if (range->memobj) {
 			// XXX: temporary of temporary

kernel/syscall.c

@@ -3604,8 +3604,9 @@ SYSCALL_DECLARE(exit)
 	
 	proc->ftn->status = PS_ZOMBIE;
 	
+	release_fork_tree_node(proc->ftn->parent);
 	release_fork_tree_node(proc->ftn);
-	release_process(proc);
+	//release_process(proc);
 
 	schedule();