Clean up execve locking:

- Grab the vnode object early in exec when we still have the vnode lock.
 - Cache the object in the image_params.
 - Make use of the cached object in imgact_*.c

sys/kern/imgact_aout.c

@@ -186,9 +186,9 @@ exec_aout_imgact(imgp)
 	vmspace = imgp->proc->p_vmspace;
 
 	vp = imgp->vp;
+	object = imgp->object;
 	map = &vmspace->vm_map;
 	vm_map_lock(map);
-	VOP_GETVOBJECT(vp, &object);
 	vm_object_reference(object);
 
 	text_end = virtual_offset + a_out->a_text;

sys/kern/imgact_elf.c

@@ -76,7 +76,7 @@ static int elf_freebsd_fixup(register_t **stack_base,
 static int elf_load_file(struct proc *p, const char *file, u_long *addr,
     u_long *entry);
 static int elf_load_section(struct proc *p,
-    struct vmspace *vmspace, struct vnode *vp,
+    struct vmspace *vmspace, struct vnode *vp, vm_object_t object,
     vm_offset_t offset, caddr_t vmaddr, size_t memsz, size_t filsz,
     vm_prot_t prot);
 static int exec_elf_imgact(struct image_params *imgp);
@@ -186,19 +186,17 @@ elf_check_header(const Elf_Ehdr *hdr)
 }
 
 static int
-elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_offset_t offset, caddr_t vmaddr, size_t memsz, size_t filsz, vm_prot_t prot)
+elf_load_section(struct proc *p, struct vmspace *vmspace, struct vnode *vp, vm_object_t object, vm_offset_t offset, caddr_t vmaddr, size_t memsz, size_t filsz, vm_prot_t prot)
 {
 	size_t map_len;
 	vm_offset_t map_addr;
 	int error, rv;
 	size_t copy_len;
-	vm_object_t object;
 	vm_offset_t file_addr;
 	vm_offset_t data_buf = 0;
 
 	GIANT_REQUIRED;
 
-	VOP_GETVOBJECT(vp, &object);
 	error = 0;
 
 	/*
@@ -356,6 +354,7 @@ elf_load_file(struct proc *p, const char *file, u_long *addr, u_long *entry)
 	imgp->attr = attr;
 	imgp->firstpage = NULL;
 	imgp->image_header = (char *)kmem_alloc_wait(exec_map, PAGE_SIZE);
+	imgp->object = NULL;
 
 	if (imgp->image_header == NULL) {
 		nd->ni_vp = NULL;
@@ -389,6 +388,9 @@ elf_load_file(struct proc *p, const char *file, u_long *addr, u_long *entry)
 	 */
 	if (error == 0)
 		nd->ni_vp->v_flag |= VTEXT;
+	VOP_GETVOBJECT(nd->ni_vp, &imgp->object);
+	vm_object_reference(imgp->object);
+
 	VOP_UNLOCK(nd->ni_vp, 0, curthread); /* XXXKSE */
 	if (error)
                 goto fail;
@@ -425,6 +427,7 @@ elf_load_file(struct proc *p, const char *file, u_long *addr, u_long *entry)
   				prot |= VM_PROT_READ;
 
 			if ((error = elf_load_section(p, vmspace, nd->ni_vp,
+						     imgp->object,
   						     phdr[i].p_offset,
   						     (caddr_t)phdr[i].p_vaddr +
 							rbase,
@@ -449,6 +452,9 @@ elf_load_file(struct proc *p, const char *file, u_long *addr, u_long *entry)
 	if (imgp->image_header)
 		kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header,
 			PAGE_SIZE);
+	if (imgp->object)
+		vm_object_deallocate(imgp->object);
+
 	if (nd->ni_vp)
 		vrele(nd->ni_vp);
 
@@ -540,6 +546,7 @@ exec_elf_imgact(struct image_params *imgp)
 
 			if ((error = elf_load_section(imgp->proc,
 						     vmspace, imgp->vp,
+						     imgp->object,
   						     phdr[i].p_offset,
   						     (caddr_t)phdr[i].p_vaddr,
   						     phdr[i].p_memsz,

sys/kern/kern_exec.c

@@ -182,6 +182,7 @@ execve(td, uap)
 	imgp->interpreter_name[0] = '\0';
 	imgp->auxargs = NULL;
 	imgp->vp = NULL;
+	imgp->object = NULL;
 	imgp->firstpage = NULL;
 	imgp->ps_strings = 0;
 	imgp->auxarg_size = 0;
@@ -227,6 +228,8 @@ execve(td, uap)
 		VOP_UNLOCK(imgp->vp, 0, td);
 		goto exec_fail_dealloc;
 	}
+	VOP_GETVOBJECT(imgp->vp, &imgp->object);
+	vm_object_reference(imgp->object);
 
 	error = exec_map_first_page(imgp);
 	VOP_UNLOCK(imgp->vp, 0, td);
@@ -270,6 +273,8 @@ execve(td, uap)
 		/* free name buffer and old vnode */
 		NDFREE(ndp, NDF_ONLY_PNBUF);
 		vrele(ndp->ni_vp);
+		vm_object_deallocate(imgp->object);
+		imgp->object = NULL;
 		/* set new name to that of the interpreter */
 		NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
 		    UIO_SYSSPACE, imgp->interpreter_name, td);
@@ -519,6 +524,9 @@ execve(td, uap)
 		vrele(imgp->vp);
 	}
 
+	if (imgp->object)
+		vm_object_deallocate(imgp->object);
+
 	if (error == 0)
 		goto done2;
 

sys/sys/imgact.h

@@ -38,10 +38,13 @@
 
 #define MAXSHELLCMDLEN	128
 
+struct vm_object;
+
 struct image_params {
 	struct proc *proc;	/* our process struct */
 	struct execve_args *uap; /* syscall arguments */
 	struct vnode *vp;	/* pointer to vnode of file to exec */
+	struct vm_object *object;	/* The vm object for this vp */
 	struct vattr *attr;	/* attributes of file */
 	const char *image_header; /* head of file to exec */
 	char *stringbase;	/* base address of tmp string storage */