5 files changed, 30 insertions, 29 deletions

diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 4e2eaa98f3aa..03d8cbc6bc1e 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 
 #include "opt_kdtrace.h"
 #include "opt_ktrace.h"
+#include "opt_kstack_pages.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -276,25 +277,29 @@ norfproc_fail:
 
 	mem_charged = 0;
 	vm2 = NULL;
+	if (pages == 0)
+		pages = KSTACK_PAGES;
 	/* Allocate new proc. */
 	newproc = uma_zalloc(proc_zone, M_WAITOK);
-	if (TAILQ_EMPTY(&newproc->p_threads)) {
-		td2 = thread_alloc();
+	td2 = FIRST_THREAD_IN_PROC(newproc);
+	if (td2 == NULL) {
+		td2 = thread_alloc(pages);
 		if (td2 == NULL) {
 			error = ENOMEM;
 			goto fail1;
 		}
 		proc_linkup(newproc, td2);
-	} else
-		td2 = FIRST_THREAD_IN_PROC(newproc);
-
-	/* Allocate and switch to an alternate kstack if specified. */
-	if (pages != 0) {
-		if (!vm_thread_new_altkstack(td2, pages)) {
-			error = ENOMEM;
-			goto fail1;
+	} else {
+		if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) {
+			if (td2->td_kstack != 0)
+				vm_thread_dispose(td2);
+			if (!thread_alloc_stack(td2, pages)) {
+				error = ENOMEM;
+				goto fail1;
+			}
 		}
 	}
+
 	if ((flags & RFMEM) == 0) {
 		vm2 = vmspace_fork(p1->p_vmspace, &mem_charged);
 		if (vm2 == NULL) {
diff --git a/sys/kern/kern_kthread.c b/sys/kern/kern_kthread.c
index 109283216810..3c5248ebbb6e 100644
--- a/sys/kern/kern_kthread.c
+++ b/sys/kern/kern_kthread.c
@@ -256,7 +256,7 @@ kthread_add(void (*func)(void *), void *arg, struct proc *p,
 	}
 
 	/* Initialize our new td  */
-	newtd = thread_alloc();
+	newtd = thread_alloc(pages);
 	if (newtd == NULL)
 		return (ENOMEM);
 
@@ -282,9 +282,6 @@ kthread_add(void (*func)(void *), void *arg, struct proc *p,
 
 	newtd->td_pflags |= TDP_KTHREAD;
 	newtd->td_ucred = crhold(p->p_ucred);
-	/* Allocate and switch to an alternate kstack if specified. */
-	if (pages != 0)
-		vm_thread_new_altkstack(newtd, pages);
 
 	/* this code almost the same as create_thread() in kern_thr.c */
 	PROC_LOCK(p);
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index cdbc01207ea1..e012a3ed4c00 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -203,14 +203,6 @@ proc_dtor(void *mem, int size, void *arg)
 #endif
 		/* Free all OSD associated to this thread. */
 		osd_thread_exit(td);
-
-		/* Dispose of an alternate kstack, if it exists.
-		 * XXX What if there are more than one thread in the proc?
-		 *     The first thread in the proc is special and not
-		 *     freed, so you gotta do this here.
-		 */
-		if (((p->p_flag & P_KTHREAD) != 0) && (td->td_altkstack != 0))
-			vm_thread_dispose_altkstack(td);
 	}
 	EVENTHANDLER_INVOKE(process_dtor, p);
 	if (p->p_ksi != NULL)
@@ -767,8 +759,6 @@ fill_kinfo_proc_only(struct proc *p, struct kinfo_proc *kp)
 		FOREACH_THREAD_IN_PROC(p, td0) {
 			if (!TD_IS_SWAPPED(td0))
 				kp->ki_rssize += td0->td_kstack_pages;
-			if (td0->td_altkstack_obj != NULL)
-				kp->ki_rssize += td0->td_altkstack_pages;
 		}
 		kp->ki_swrss = vm->vm_swrss;
 		kp->ki_tsize = vm->vm_tsize;
diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index c478c63bd9bc..630069b59407 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -176,7 +176,7 @@ create_thread(struct thread *td, mcontext_t *ctx,
 	}
 
 	/* Initialize our td */
-	newtd = thread_alloc();
+	newtd = thread_alloc(0);
 	if (newtd == NULL)
 		return (ENOMEM);
 
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index d47bd8cef8b6..4f3b32cdd0ae 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -283,7 +283,7 @@ thread_reap(void)
  * Allocate a thread.
  */
 struct thread *
-thread_alloc(void)
+thread_alloc(int pages)
 {
 	struct thread *td;
 
@@ -291,7 +291,7 @@ thread_alloc(void)
 
 	td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
 	KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
-	if (!vm_thread_new(td, 0)) {
+	if (!vm_thread_new(td, pages)) {
 		uma_zfree(thread_zone, td);
 		return (NULL);
 	}
@@ -299,6 +299,17 @@ thread_alloc(void)
 	return (td);
 }
 
+int
+thread_alloc_stack(struct thread *td, int pages)
+{
+
+	KASSERT(td->td_kstack == 0,
+	    ("thread_alloc_stack called on a thread with kstack"));
+	if (!vm_thread_new(td, pages))
+		return (0);
+	cpu_thread_alloc(td);
+	return (1);
+}
 
 /*
  * Deallocate a thread.
@@ -312,8 +323,6 @@ thread_free(struct thread *td)
 		cpuset_rel(td->td_cpuset);
 	td->td_cpuset = NULL;
 	cpu_thread_free(td);
-	if (td->td_altkstack != 0)
-		vm_thread_dispose_altkstack(td);
 	if (td->td_kstack != 0)
 		vm_thread_dispose(td);
 	uma_zfree(thread_zone, td);