proc_pgmaps must be rcu_freed, and pgmap_list_.enumerate must have scoped_gc_epoch

b94e9aa3 · Silas Boyd-Wickizer · 277f2b6c · b94e9aa3 · b94e9aa3 · b94e9aa3
--- a/include/proc.hh
+++ b/include/proc.hh
@@ -20,12 +20,13 @@ struct pgmap;
  }
 #endif

-struct proc_pgmap : public referenced {
+struct proc_pgmap : public referenced, public rcu_freed {
  pgmap* const pml4;
  vmap* const vmp;

  static proc_pgmap* alloc(vmap* vmap);
-  virtual void onzero() const { delete this; }
+  virtual void onzero() const;
+  virtual void do_gc(void) { delete this; }
  proc_pgmap& operator=(const proc_pgmap&) = delete;
  proc_pgmap(const proc_pgmap& x) = delete;
 private:

--- a/kernel/proc.cc
+++ b/kernel/proc.cc
@@ -31,7 +31,7 @@ struct kstack_tag kstack_tag[NCPU];
 enum { sched_debug = 0 };

 proc_pgmap::proc_pgmap(vmap* vmap)
-  : pml4(setupkvm()), vmp(vmap)
+  : rcu_freed("proc_pgmap"), pml4(setupkvm()), vmp(vmap)
 {
  if (pml4 == nullptr) {
    cprintf("proc_pgmap::proc_pgmap: setupkvm out of memory\n");
@@ -50,11 +50,18 @@ proc_pgmap::alloc(vmap* vmap)

 proc_pgmap::~proc_pgmap(void)
 {
-  vmp->rem_pgmap(this);
-  vmp->decref();
  freevm(pml4);
 }

+void
+proc_pgmap::onzero() const
+{
+  proc_pgmap* p = (proc_pgmap*) this;
+  p->vmp->rem_pgmap(p);
+  p->vmp->decref();
+  gc_delayed(p);
+}
+
 proc::proc(int npid) :
  rcu_freed("proc"), vmap(0), uwq(0), worker(0), kstack(0),
  pid(npid), parent(0), tf(0), context(0), killed(0),

--- a/kernel/vm.cc
+++ b/kernel/vm.cc
@@ -487,14 +487,15 @@ again:
  };

  if (replaced) {
-    if (updateall)
+    if (updateall) {
+      scoped_gc_epoch gc;
      pgmap_list_.enumerate([&](proc_pgmap* const &p,
                                proc_pgmap* const &x)->bool
      {
        updatepages(p->pml4, e->vma_start, e->vma_end, update);
        return false;
      });
-    else
+    } else
      updatepages(pgmap->pml4, e->vma_start, e->vma_end, update);      
  }

@@ -558,14 +559,15 @@ vmap::remove(uptr vma_start, uptr len, proc_pgmap* pgmap)
    }
  };

-  if (updateall)
+  if (updateall) {
+    scoped_gc_epoch gc;
    pgmap_list_.enumerate([&](proc_pgmap* const &p,
                              proc_pgmap* const &x)->bool
    {
      updatepages(p->pml4, vma_start, vma_start + len, update);
      return false;
    });
-  else
+  } else
    updatepages(pgmap->pml4, vma_start, vma_start + len, update);    

  if (tlb_shootdown && needtlb) {