Implement global and per-uid accounting of the anonymous memory. Add

rlimit RLIMIT_SWAP that limits the amount of swap that may be reserved
for the uid.

The accounting information (charge) is associated with either map entry,
or vm object backing the entry, assuming the object is the first one
in the shadow chain and entry does not require COW. Charge is moved
from entry to object on allocation of the object, e.g. during the mmap,
assuming the object is allocated, or on the first page fault on the
entry. It moves back to the entry on forks due to COW setup.

The per-entry granularity of accounting makes the charge process fair
for processes that change uid during lifetime, and decrements charge
for proper uid when region is unmapped.

The interface of vm_pager_allocate(9) is extended by adding struct ucred *,
that is used to charge appropriate uid when allocation if performed by
kernel, e.g. md(4).

Several syscalls, among them is fork(2), may now return ENOMEM when
global or per-uid limits are enforced.

In collaboration with:	pho
Reviewed by:	alc
Approved by:	re (kensmith)

1 files changed, 21 insertions, 4 deletions

diff --git a/sys/vm/default_pager.c b/sys/vm/default_pager.c
index 485571b..ceb2c77 100644
--- a/sys/vm/default_pager.c
+++ b/sys/vm/default_pager.c
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/lock.h>
 #include <sys/proc.h>
+#include <sys/resourcevar.h>
 #include <sys/mutex.h>
 
 #include <vm/vm.h>
@@ -53,7 +54,7 @@ __FBSDID("$FreeBSD$");
 #include <vm/swap_pager.h>
 
 static vm_object_t default_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
-		vm_ooffset_t);
+    vm_ooffset_t, struct ucred *);
 static void default_pager_dealloc(vm_object_t);
 static int default_pager_getpages(vm_object_t, vm_page_t *, int, int);
 static void default_pager_putpages(vm_object_t, vm_page_t *, int, 
@@ -76,12 +77,28 @@ struct pagerops defaultpagerops = {
  */
 static vm_object_t
 default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
-		    vm_ooffset_t offset)
+    vm_ooffset_t offset, struct ucred *cred)
 {
+	vm_object_t object;
+	struct uidinfo *uip;
+
 	if (handle != NULL)
 		panic("default_pager_alloc: handle specified");
-
-	return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(round_page(offset + size)));
+	if (cred != NULL) {
+		uip = cred->cr_ruidinfo;
+		if (!swap_reserve_by_uid(size, uip))
+			return (NULL);
+		uihold(uip);
+	}
+	object = vm_object_allocate(OBJT_DEFAULT,
+	    OFF_TO_IDX(round_page(offset + size)));
+	if (cred != NULL) {
+		VM_OBJECT_LOCK(object);
+		object->uip = uip;
+		object->charge = size;
+		VM_OBJECT_UNLOCK(object);
+	}
+	return (object);
 }
 
 /*