Fix for the panic("vm_thread_new: kstack allocation failed") and

silent NULL pointer dereference in the i386 and sparc64 pmap_pinit()
when the kmem_alloc_nofault() failed to allocate address space. Both
functions now return error instead of panicing or dereferencing NULL.

As consequence, vmspace_exec() and vmspace_unshare() returns the errno
int. struct vmspace arg was added to vm_forkproc() to avoid dealing
with failed allocation when most of the fork1() job is already done.

The kernel stack for the thread is now set up in the thread_alloc(),
that itself may return NULL. Also, allocation of the first process
thread is performed in the fork1() to properly deal with stack
allocation failure. proc_linkup() is separated into proc_linkup()
called from fork1(), and proc_linkup0(), that is used to set up the
kernel process (was known as swapper).

In collaboration with:	Peter Holm
Reviewed by:	jhb

2 files changed, 3 insertions, 2 deletions

diff --git a/sys/sun4v/sun4v/machdep.c b/sys/sun4v/sun4v/machdep.c
index eb3d3c9..16a508a 100644
--- a/sys/sun4v/sun4v/machdep.c
+++ b/sys/sun4v/sun4v/machdep.c
@@ -364,7 +364,7 @@ sparc64_init(caddr_t mdp, u_long o1, u_long o2, u_long o3, ofw_vec_t *vec)
 	 * Initialize proc0 stuff (p_contested needs to be done early).
 	 */
 
-	proc_linkup(&proc0, &thread0);
+	proc_linkup0(&proc0, &thread0);
 	proc0.p_md.md_sigtramp = NULL;
 	proc0.p_md.md_utrap = NULL;
 	frame0.tf_tstate = TSTATE_IE | TSTATE_PEF | TSTATE_PRIV;
diff --git a/sys/sun4v/sun4v/pmap.c b/sys/sun4v/sun4v/pmap.c
index 917eb1a..ecfe3db 100644
--- a/sys/sun4v/sun4v/pmap.c
+++ b/sys/sun4v/sun4v/pmap.c
@@ -1703,7 +1703,7 @@ pmap_pinit0(pmap_t pmap)
  * Initialize a preallocated and zeroed pmap structure, such as one in a
  * vmspace structure.
  */
-void
+int
 pmap_pinit(pmap_t pmap)
 {
 	int i;
@@ -1723,6 +1723,7 @@ pmap_pinit(pmap_t pmap)
 	TAILQ_INIT(&pmap->pm_pvlist);
 	PMAP_LOCK_INIT(pmap);
 	bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
+	return (1);
 }
 
 /*