cannot assume kmem refers to same ptr, unless interrupts are disabled

40ba7672 · Nickolai Zeldovich · db4ad0cd · 40ba7672 · 40ba7672
--- a/kalloc.c
+++ b/kalloc.c
@@ -22,6 +22,9 @@ kmemprint(void)
 {
  cprintf("free pages: [ ");
  for (uint i = 0; i < NCPU; i++)
+    if (i == cpunum())
+      cprintf("<%d> ", kmems[i].nfree);
+    else
      cprintf("%d ", kmems[i].nfree);
  cprintf("]\n");
 }
@@ -59,11 +62,12 @@ kfree(char *v)
  // Fill with junk to catch dangling refs.
  memset(v, 1, PGSIZE);

-  acquire(&kmem->lock);
+  struct kmem *m = kmem;
+  acquire(&m->lock);
  r = (struct run*)v;
-  r->next = kmem->freelist;
-  kmem->freelist = r;
-  kmem->nfree++;
+  r->next = m->freelist;
+  m->freelist = r;
+  m->nfree++;
  mtrace_label_register(mtrace_label_block,
 			r,
 			0,
@@ -71,7 +75,7 @@ kfree(char *v)
 			0,
 			RET_EIP());

-  release(&kmem->lock);
+  release(&m->lock);
 }

 // Allocate one 4096-byte page of physical memory.
@@ -84,8 +88,10 @@ kalloc(void)

  //  cprintf("%d: kalloc 0x%x 0x%x 0x%x 0x%x 0%x\n", cpu->id, kmem, &kmems[cpu->id], kmem->freelist, PHYSTOP, kmems[1].freelist);

+  uint startcpu = cpunum();
  for (uint i = 0; r == 0 && i < NCPU; i++) {
-    struct kmem *m = &kmems[(i + cpunum()) % NCPU];
+    int cn = (i + startcpu) % NCPU;
+    struct kmem *m = &kmems[cn];
    acquire(&m->lock);
    r = m->freelist;
    if (r) {

--- a/param.h
+++ b/param.h
@@ -8,6 +8,6 @@
 #define NDEV         10  // maximum major device number
 #define ROOTDEV       1  // device number of file system root disk
 #define USERTOP  0xA0000 // end of user address space
-#define PHYSTOP  0x1000000 // use phys mem up to here as free pool
+#define PHYSTOP  0x10000000 // use phys mem up to here as free pool
 #define MAXARG       32  // max exec arguments
 #define MAXNAME      16  // max string names