Introduce a global lock for the vm subsystem (vm_mtx).

vm_mtx does not recurse and is required for most low level
vm operations.

faults can not be taken without holding Giant.

Memory subsystems can now call the base page allocators safely.

Almost all atomic ops were removed as they are covered under the
vm mutex.

Alpha and ia64 now need to catch up to i386's trap handlers.

FFS and NFS have been tested, other filesystems will need minor
changes (grabbing the vm lock when twiddling page properties).

Reviewed (partially) by: jake, jhb

5 files changed, 18 insertions, 1 deletions

diff --git a/sys/fs/coda/coda_namecache.c b/sys/fs/coda/coda_namecache.c
index 3b73a67..9dfaf19 100644
--- a/sys/fs/coda/coda_namecache.c
+++ b/sys/fs/coda/coda_namecache.c
@@ -81,6 +81,7 @@
 #include <sys/errno.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
+#include <sys/mutex.h>
 #include <sys/ucred.h>
 
 #include <vm/vm.h>
diff --git a/sys/fs/procfs/procfs_map.c b/sys/fs/procfs/procfs_map.c
index 5e4a30c..5c21993 100644
--- a/sys/fs/procfs/procfs_map.c
+++ b/sys/fs/procfs/procfs_map.c
@@ -42,6 +42,7 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/lock.h>
+#include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/vnode.h>
 
diff --git a/sys/fs/procfs/procfs_mem.c b/sys/fs/procfs/procfs_mem.c
index 3a2f8d2..1e28870 100644
--- a/sys/fs/procfs/procfs_mem.c
+++ b/sys/fs/procfs/procfs_mem.c
@@ -48,6 +48,7 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/lock.h>
+#include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/ptrace.h>
 #include <sys/user.h>
@@ -88,8 +89,14 @@ procfs_rwmem(curp, p, uio)
 	 * usage in that process can be messed up.
 	 */
 	vm = p->p_vmspace;
-	if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
+	if ((p->p_flag & P_WEXIT))
 		return EFAULT;
+
+	mtx_lock(&vm_mtx);
+	if (vm->vm_refcnt < 1) {
+		mtx_unlock(&vm_mtx);
+		return EFAULT;
+	}
 	++vm->vm_refcnt;
 	/*
 	 * The map we want...
@@ -207,7 +214,9 @@ procfs_rwmem(curp, p, uio)
 		/*
 		 * Now do the i/o move.
 		 */
+		mtx_unlock(&vm_mtx);
 		error = uiomove((caddr_t)(kva + page_offset), len, uio);
+		mtx_lock(&vm_mtx);
 
 		pmap_kremove(kva);
 
@@ -226,6 +235,7 @@ procfs_rwmem(curp, p, uio)
 
 	kmem_free(kernel_map, kva, PAGE_SIZE);
 	vmspace_free(vm);
+	mtx_unlock(&vm_mtx);
 	return (error);
 }
 
diff --git a/sys/fs/specfs/spec_vnops.c b/sys/fs/specfs/spec_vnops.c
index 2940f40..ba81229 100644
--- a/sys/fs/specfs/spec_vnops.c
+++ b/sys/fs/specfs/spec_vnops.c
@@ -731,6 +731,8 @@ spec_getpages(ap)
 	cnt.v_vnodein++;
 	cnt.v_vnodepgsin += pcount;
 
+	mtx_unlock(&vm_mtx);
+	mtx_lock(&Giant);
 	/* Do the input. */
 	BUF_STRATEGY(bp);
 
@@ -741,6 +743,8 @@ spec_getpages(ap)
 		tsleep(bp, PVM, "spread", 0);
 
 	splx(s);
+	mtx_unlock(&Giant);
+	mtx_lock(&vm_mtx);
 
 	if ((bp->b_ioflags & BIO_ERROR) != 0) {
 		if (bp->b_error)
diff --git a/sys/fs/unionfs/union_subr.c b/sys/fs/unionfs/union_subr.c
index 869818f..3ac98bf 100644
--- a/sys/fs/unionfs/union_subr.c
+++ b/sys/fs/unionfs/union_subr.c
@@ -45,6 +45,7 @@
 #include <sys/filedesc.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
+#include <sys/mutex.h>
 #include <sys/malloc.h>
 #include <sys/module.h>
 #include <sys/mount.h>