Revert r253939:

We cannot busy a page before doing pagefaults.
Infact, it can deadlock against vnode lock, as it tries to vget().
Other functions, right now, have an opposite lock ordering, like
vm_object_sync(), which acquires the vnode lock first and then
sleeps on the busy mechanism.

Before this patch is reinserted we need to break this ordering.

Sponsored by:	EMC / Isilon storage division
Reported by:	kib

3 files changed, 10 insertions, 11 deletions

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 9533635..61a2aef 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -378,7 +378,7 @@ __elfN(map_partial)(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
 		off = offset - trunc_page(offset);
 		error = copyout((caddr_t)sf_buf_kva(sf) + off, (caddr_t)start,
 		    end - start);
-		vm_imgact_unmap_page(object, sf);
+		vm_imgact_unmap_page(sf);
 		if (error) {
 			return (KERN_FAILURE);
 		}
@@ -433,7 +433,7 @@ __elfN(map_insert)(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
 					sz = PAGE_SIZE - off;
 				error = copyout((caddr_t)sf_buf_kva(sf) + off,
 				    (caddr_t)start, sz);
-				vm_imgact_unmap_page(object, sf);
+				vm_imgact_unmap_page(sf);
 				if (error) {
 					return (KERN_FAILURE);
 				}
@@ -553,7 +553,7 @@ __elfN(load_section)(struct image_params *imgp, vm_offset_t offset,
 		    trunc_page(offset + filsz);
 		error = copyout((caddr_t)sf_buf_kva(sf) + off,
 		    (caddr_t)map_addr, copy_len);
-		vm_imgact_unmap_page(object, sf);
+		vm_imgact_unmap_page(sf);
 		if (error) {
 			return (error);
 		}
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 0c8b0c1..c0e1435 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -973,7 +973,7 @@ exec_map_first_page(imgp)
 		vm_page_wakeup(ma[0]);
 	}
 	vm_page_lock(ma[0]);
-	vm_page_wire(ma[0]);
+	vm_page_hold(ma[0]);
 	vm_page_unlock(ma[0]);
 	VM_OBJECT_WUNLOCK(object);
 
@@ -994,7 +994,7 @@ exec_unmap_first_page(imgp)
 		sf_buf_free(imgp->firstpage);
 		imgp->firstpage = NULL;
 		vm_page_lock(m);
-		vm_page_unwire(m, 0);
+		vm_page_unhold(m);
 		vm_page_unlock(m);
 	}
 }
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index 33fac71..5508dcf 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -263,7 +263,6 @@ proc_rwmem(struct proc *p, struct uio *uio)
 	writing = uio->uio_rw == UIO_WRITE;
 	reqprot = writing ? VM_PROT_COPY | VM_PROT_READ : VM_PROT_READ;
 	fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL;
-	fault_flags |= VM_FAULT_IOBUSY;
 
 	/*
 	 * Only map in one page at a time.  We don't have to, but it
@@ -288,9 +287,9 @@ proc_rwmem(struct proc *p, struct uio *uio)
 		len = min(PAGE_SIZE - page_offset, uio->uio_resid);
 
 		/*
-		 * Fault and busy the page on behalf of the process.
+		 * Fault and hold the page on behalf of the process.
 		 */
-		error = vm_fault_handle(map, pageno, reqprot, fault_flags, &m);
+		error = vm_fault_hold(map, pageno, reqprot, fault_flags, &m);
 		if (error != KERN_SUCCESS) {
 			if (error == KERN_RESOURCE_SHORTAGE)
 				error = ENOMEM;
@@ -316,9 +315,9 @@ proc_rwmem(struct proc *p, struct uio *uio)
 		/*
 		 * Release the page.
 		 */
-		VM_OBJECT_WLOCK(m->object);
-		vm_page_io_finish(m);
-		VM_OBJECT_WUNLOCK(m->object);
+		vm_page_lock(m);
+		vm_page_unhold(m);
+		vm_page_unlock(m);
 
 	} while (error == 0 && uio->uio_resid > 0);