try to fix RACCT_RSS accounting

There could be a race between the vm daemon setting RACCT_RSS based on
the vm space and vmspace_exit (called from exit1) resetting RACCT_RSS to
zero.  In that case we can get a zombie process with non-zero RACCT_RSS.
If the process is jailed, that may break accounting for the jail.
There could be other consequences.

Fix this race in the vm daemon by updating RACCT_RSS only when a process
is in the normal state.  Also, make accounting a little bit more
accurate by refreshing the page resident count after calling
vm_pageout_map_deactivate_pages().
Finally, add an assert that the RSS is zero when a process is reaped.

PR:		210315
Reviewed by:	trasz
Differential Revision: https://reviews.freebsd.org/D9464

1 files changed, 4 insertions, 1 deletions

diff --git a/sys/kern/kern_racct.c b/sys/kern/kern_racct.c
index 03677663d806..5dbeae995635 100644
--- a/sys/kern/kern_racct.c
+++ b/sys/kern/kern_racct.c
@@ -1010,10 +1010,13 @@ racct_proc_exit(struct proc *p)
 	racct_set_locked(p, RACCT_CPU, runtime, 0);
 	racct_add_cred_locked(p->p_ucred, RACCT_PCTCPU, pct);
 
+	KASSERT(p->p_racct->r_resources[RACCT_RSS] == 0,
+	    ("process reaped with %ju allocated for RSS\n",
+	    p->p_racct->r_resources[RACCT_RSS]));
 	for (i = 0; i <= RACCT_MAX; i++) {
 		if (p->p_racct->r_resources[i] == 0)
 			continue;
-	    	if (!RACCT_IS_RECLAIMABLE(i))
+		if (!RACCT_IS_RECLAIMABLE(i))
 			continue;
 		racct_set_locked(p, i, 0, 0);
 	}