From be7d4ac586a2784996ef024f81e0937b31652a1d Mon Sep 17 00:00:00 2001
From: Edward Tomasz Napierala <trasz@FreeBSD.org>
Date: Sun, 22 Oct 2017 10:35:29 +0000
Subject: [PATCH] Add OID for the vm.overcommit sysctl. This makes it possible
 to remove one call to sysctl(2) from jemalloc startup code. (That also
 requires changes to jemalloc, but I plan to push those to upstream first.)

Reviewed by:	kib
MFC after:	2 weeks
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D12745
---
 lib/libc/gen/sysctl.3 | 6 +++++-
 sys/vm/swap_pager.c   | 2 +-
 sys/vm/vm_param.h     | 3 ++-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/libc/gen/sysctl.3 b/lib/libc/gen/sysctl.3
index 959573ec9623..ba1cd8f2a13f 100644
--- a/lib/libc/gen/sysctl.3
+++ b/lib/libc/gen/sysctl.3
@@ -28,7 +28,7 @@
 .\"	@(#)sysctl.3	8.4 (Berkeley) 5/9/95
 .\" $FreeBSD$
 .\"
-.Dd September 10, 2015
+.Dd October 22, 2017
 .Dt SYSCTL 3
 .Os
 .Sh NAME
@@ -741,6 +741,7 @@ privilege may change the value.
 .It Dv VM_V_FREE_TARGET Ta integer Ta yes
 .It Dv VM_V_INACTIVE_TARGET Ta integer Ta yes
 .It Dv VM_V_PAGEOUT_FREE_MIN Ta integer Ta yes
+.It Dv VM_OVERCOMMIT Ta integer Ta yes
 .El
 .Bl -tag -width 6n
 .It Li VM_LOADAVG
@@ -773,6 +774,9 @@ process address space when needed.
 .It Li VM_V_PAGEOUT_FREE_MIN
 If the amount of free and cache memory falls below this value, the
 pageout daemon will enter "memory conserving mode" to avoid deadlock.
+.It Li VM_OVERCOMMIT
+Overcommit behaviour, as described in
+.Xr tuning 7 .
 .El
 .Sh RETURN VALUES
 .Rv -std
diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index d3cc1330a08d..02891e90880f 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -157,7 +157,7 @@ static vm_ooffset_t swap_reserved;
 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0,
     "Amount of swap storage needed to back all allocated anonymous memory.");
 static int overcommit = 0;
-SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0,
+SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0,
     "Configure virtual memory overcommit behavior. See tuning(7) "
     "for details.");
 static unsigned long swzone;
diff --git a/sys/vm/vm_param.h b/sys/vm/vm_param.h
index 8ca83bf18ddf..ff36bbb6d1d8 100644
--- a/sys/vm/vm_param.h
+++ b/sys/vm/vm_param.h
@@ -84,7 +84,8 @@
 #define VM_V_PAGEOUT_FREE_MIN	9	/* vm_cnt.v_pageout_free_min */
 #define	VM_OBSOLETE_10		10	/* pageout algorithm */
 #define VM_SWAPPING_ENABLED	11	/* swapping enabled */
-#define	VM_MAXID		12	/* number of valid vm ids */
+#define VM_OVERCOMMIT		12	/* vm.overcommit */
+#define	VM_MAXID		13	/* number of valid vm ids */
 
 /*
  * Structure for swap device statistics