From f88a4ea9801bf098018fd438293d6f7cf7466535 Mon Sep 17 00:00:00 2001
From: miod <miod@openbsd.org>
Date: Sat, 10 Sep 2022 20:35:28 +0000
Subject: [PATCH] Remove pmap_collect() when a no-op, define
 __HAVE_PMAP_COLLECT otherwise. Use that define to shunt
 uvm_swapout_threads(), which is a noop when pmap_collect() does nothing.

ok mpi@
---
 sys/arch/alpha/include/pmap.h       |  4 +++-
 sys/arch/amd64/amd64/pmap.c         |  7 ++++---
 sys/arch/arm/arm/pmap7.c            | 17 +----------------
 sys/arch/arm64/arm64/pmap.c         | 20 +-------------------
 sys/arch/hppa/hppa/pmap.c           |  9 +--------
 sys/arch/hppa/include/param.h       |  3 +--
 sys/arch/m88k/include/pmap.h        |  3 ++-
 sys/arch/mips64/include/pmap.h      |  4 +++-
 sys/arch/powerpc/powerpc/pmap.c     | 20 +-------------------
 sys/arch/powerpc64/powerpc64/pmap.c |  7 +------
 sys/arch/riscv64/riscv64/pmap.c     | 20 +-------------------
 sys/arch/sh/include/pmap.h          |  3 +--
 sys/arch/sparc64/include/pmap.h     |  2 ++
 sys/arch/sparc64/sparc64/pmap.c     |  4 +---
 sys/uvm/uvm_glue.c                  |  6 +++++-
 sys/uvm/uvm_pdaemon.c               |  4 ++--
 sys/uvm/uvm_pmap.h                  |  4 ++--
 17 files changed, 32 insertions(+), 105 deletions(-)

diff --git a/sys/arch/alpha/include/pmap.h b/sys/arch/alpha/include/pmap.h
index d611156bbc3..cfa4cc2400f 100644
--- a/sys/arch/alpha/include/pmap.h
+++ b/sys/arch/alpha/include/pmap.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: pmap.h,v 1.40 2016/04/20 05:24:18 landry Exp $ */
+/* $OpenBSD: pmap.h,v 1.41 2022/09/10 20:35:28 miod Exp $ */
 /* $NetBSD: pmap.h,v 1.37 2000/11/19 03:16:35 thorpej Exp $ */
 
 /*-
@@ -197,6 +197,8 @@ extern	pt_entry_t *VPT;		/* Virtual Page Table */
 
 paddr_t vtophys(vaddr_t);
 
+#define	__HAVE_PMAP_COLLECT
+
 /* Machine-specific functions. */
 void	pmap_bootstrap(paddr_t ptaddr, u_int maxasn, u_long ncpuids);
 int	pmap_emulate_reference(struct proc *p, vaddr_t v, int user, int type);
diff --git a/sys/arch/amd64/amd64/pmap.c b/sys/arch/amd64/amd64/pmap.c
index ad35db3a1ab..0078b47b6e4 100644
--- a/sys/arch/amd64/amd64/pmap.c
+++ b/sys/arch/amd64/amd64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.153 2022/06/30 13:51:24 mlarkin Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.154 2022/09/10 20:35:28 miod Exp $	*/
 /*	$NetBSD: pmap.c,v 1.3 2003/05/08 18:13:13 thorpej Exp $	*/
 
 /*
@@ -2206,6 +2206,7 @@ pmap_unwire(struct pmap *pmap, vaddr_t va)
 #endif
 }
 
+#if 0
 /*
  * pmap_collect: free resources held by a pmap
  *
@@ -2221,10 +2222,10 @@ pmap_collect(struct pmap *pmap)
 	 * for its entire address space.
 	 */
 
-/*	pmap_do_remove(pmap, VM_MIN_ADDRESS, VM_MAX_ADDRESS,
+	pmap_do_remove(pmap, VM_MIN_ADDRESS, VM_MAX_ADDRESS,
 	    PMAP_REMOVE_SKIPWIRED);
-*/
 }
+#endif
 
 /*
  * pmap_copy: copy mappings from one pmap to another
diff --git a/sys/arch/arm/arm/pmap7.c b/sys/arch/arm/arm/pmap7.c
index c8844b51d09..d4eb442a7dc 100644
--- a/sys/arch/arm/arm/pmap7.c
+++ b/sys/arch/arm/arm/pmap7.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap7.c,v 1.63 2022/02/21 19:15:58 kettenis Exp $	*/
+/*	$OpenBSD: pmap7.c,v 1.64 2022/09/10 20:35:28 miod Exp $	*/
 /*	$NetBSD: pmap.c,v 1.147 2004/01/18 13:03:50 scw Exp $	*/
 
 /*
@@ -1742,21 +1742,6 @@ dab_access(trapframe_t *tf, u_int fsr, u_int far, struct proc *p)
 	return 0;
 }
 
-/*
- * pmap_collect: free resources held by a pmap
- *
- * => optional function.
- * => called when a process is swapped out to free memory.
- */
-void
-pmap_collect(pmap_t pm)
-{
-	/*
-	 * Nothing to do.
-	 * We don't even need to free-up the process' L1.
-	 */
-}
-
 /*
  * Routine:	pmap_proc_iflush
  *
diff --git a/sys/arch/arm64/arm64/pmap.c b/sys/arch/arm64/arm64/pmap.c
index 0fe4b83b381..49a6308319e 100644
--- a/sys/arch/arm64/arm64/pmap.c
+++ b/sys/arch/arm64/arm64/pmap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: pmap.c,v 1.84 2022/01/10 09:20:27 kettenis Exp $ */
+/* $OpenBSD: pmap.c,v 1.85 2022/09/10 20:35:28 miod Exp $ */
 /*
  * Copyright (c) 2008-2009,2014-2016 Dale Rahn <drahn@dalerahn.com>
  *
@@ -855,24 +855,6 @@ pmap_fill_pte(pmap_t pm, vaddr_t va, paddr_t pa, struct pte_desc *pted,
 	pted->pted_pte |= flags & (PROT_READ|PROT_WRITE|PROT_EXEC);
 }
 
-/*
- * Garbage collects the physical map system for pages which are
- * no longer used. Success need not be guaranteed -- that is, there
- * may well be pages which are not referenced, but others may be collected
- * Called by the pageout daemon when pages are scarce.
- */
-void
-pmap_collect(pmap_t pm)
-{
-	/* This could return unused v->p table layers which
-	 * are empty.
-	 * could malicious programs allocate memory and eat
-	 * these wired pages? These are allocated via pool.
-	 * Are there pool functions which could be called
-	 * to lower the pool usage here?
-	 */
-}
-
 /*
  * Fill the given physical page with zeros.
  */
diff --git a/sys/arch/hppa/hppa/pmap.c b/sys/arch/hppa/hppa/pmap.c
index b1dbcf437e7..657dfffa362 100644
--- a/sys/arch/hppa/hppa/pmap.c
+++ b/sys/arch/hppa/hppa/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.177 2021/09/14 16:16:51 kettenis Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.178 2022/09/10 20:35:28 miod Exp $	*/
 
 /*
  * Copyright (c) 1998-2004 Michael Shalayeff
@@ -734,13 +734,6 @@ pmap_reference(struct pmap *pmap)
 	atomic_inc_int(&pmap->pm_obj.uo_refs);
 }
 
-void
-pmap_collect(struct pmap *pmap)
-{
-	DPRINTF(PDB_FOLLOW|PDB_PMAP, ("pmap_collect(%p)\n", pmap));
-	/* nothing yet */
-}
-
 int
 pmap_enter(struct pmap *pmap, vaddr_t va, paddr_t pa, vm_prot_t prot, int flags)
 {
diff --git a/sys/arch/hppa/include/param.h b/sys/arch/hppa/include/param.h
index c53885bb7c4..355b349c6fd 100644
--- a/sys/arch/hppa/include/param.h
+++ b/sys/arch/hppa/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.47 2018/09/14 13:58:20 claudio Exp $	*/
+/*	$OpenBSD: param.h,v 1.48 2022/09/10 20:35:28 miod Exp $	*/
 
 /*
  * Copyright (c) 1988-1994, The University of Utah and
@@ -66,6 +66,5 @@
 #endif /* _KERNEL */
 
 #define	MACHINE_STACK_GROWS_UP	1		/* stack grows to higher addresses */
-#define	__SWAP_BROKEN
 
 #endif /* _MACHINE_PARAM_H_ */
diff --git a/sys/arch/m88k/include/pmap.h b/sys/arch/m88k/include/pmap.h
index f7b038e72cf..3f35640563a 100644
--- a/sys/arch/m88k/include/pmap.h
+++ b/sys/arch/m88k/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.26 2015/07/25 20:45:05 miod Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.27 2022/09/10 20:35:28 miod Exp $	*/
 /*
  * Mach Operating System
  * Copyright (c) 1991 Carnegie Mellon University
@@ -80,6 +80,7 @@ int	pmap_translation_info(pmap_t, vaddr_t, paddr_t *, uint32_t *);
 #define	pmap_unmap_direct(va)		PHYS_TO_VM_PAGE((paddr_t)va)
 #define	__HAVE_PMAP_DIRECT
 #define	PMAP_STEAL_MEMORY
+#define	__HAVE_PMAP_COLLECT
 
 #endif	/* _KERNEL */
 
diff --git a/sys/arch/mips64/include/pmap.h b/sys/arch/mips64/include/pmap.h
index c58fa74542e..ea6cb7252e6 100644
--- a/sys/arch/mips64/include/pmap.h
+++ b/sys/arch/mips64/include/pmap.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: pmap.h,v 1.49 2021/05/01 16:11:11 visa Exp $ */
+/*      $OpenBSD: pmap.h,v 1.50 2022/09/10 20:35:28 miod Exp $ */
 
 /*
  * Copyright (c) 1987 Carnegie-Mellon University
@@ -170,6 +170,8 @@ void	pmap_page_cache(vm_page_t, u_int);
 vaddr_t	pmap_map_direct(vm_page_t);
 vm_page_t pmap_unmap_direct(vaddr_t);
 
+#define	__HAVE_PMAP_COLLECT
+
 /*
  * MD flags to pmap_enter:
  */
diff --git a/sys/arch/powerpc/powerpc/pmap.c b/sys/arch/powerpc/powerpc/pmap.c
index fae4c8c20cf..f27adad680a 100644
--- a/sys/arch/powerpc/powerpc/pmap.c
+++ b/sys/arch/powerpc/powerpc/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.176 2022/02/07 23:20:09 gkoehler Exp $ */
+/*	$OpenBSD: pmap.c,v 1.177 2022/09/10 20:35:28 miod Exp $ */
 
 /*
  * Copyright (c) 2015 Martin Pieuchot
@@ -1051,24 +1051,6 @@ pmap_clear_attrs(struct vm_page *pg, u_int flagbit)
 	return bits;
 }
 
-/*
- * Garbage collects the physical map system for pages which are 
- * no longer used. Success need not be guaranteed -- that is, there
- * may well be pages which are not referenced, but others may be collected
- * Called by the pageout daemon when pages are scarce.
- */
-void
-pmap_collect(pmap_t pm)
-{
-	/* This could return unused v->p table layers which 
-	 * are empty.
-	 * could malicious programs allocate memory and eat
-	 * these wired pages? These are allocated via pool.
-	 * Are there pool functions which could be called
-	 * to lower the pool usage here?
-	 */
-}
-
 /*
  * Fill the given physical page with zeros.
  */
diff --git a/sys/arch/powerpc64/powerpc64/pmap.c b/sys/arch/powerpc64/powerpc64/pmap.c
index 9d19c54295a..2fc2a10b378 100644
--- a/sys/arch/powerpc64/powerpc64/pmap.c
+++ b/sys/arch/powerpc64/powerpc64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.57 2021/10/12 18:06:15 kettenis Exp $ */
+/*	$OpenBSD: pmap.c,v 1.58 2022/09/10 20:35:28 miod Exp $ */
 
 /*
  * Copyright (c) 2015 Martin Pieuchot
@@ -1464,11 +1464,6 @@ pmap_unwire(pmap_t pm, vaddr_t va)
 	PMAP_VP_UNLOCK(pm);
 }
 
-void
-pmap_collect(pmap_t pm)
-{
-}
-
 void
 pmap_zero_page(struct vm_page *pg)
 {
diff --git a/sys/arch/riscv64/riscv64/pmap.c b/sys/arch/riscv64/riscv64/pmap.c
index a1dcc203222..d0413e01744 100644
--- a/sys/arch/riscv64/riscv64/pmap.c
+++ b/sys/arch/riscv64/riscv64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.22 2022/08/29 02:01:18 jsg Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.23 2022/09/10 20:35:29 miod Exp $	*/
 
 /*
  * Copyright (c) 2019-2020 Brian Bamsch <bbamsch@google.com>
@@ -760,24 +760,6 @@ pmap_fill_pte(pmap_t pm, vaddr_t va, paddr_t pa, struct pte_desc *pted,
 	pted->pted_pte |= flags & (PROT_READ|PROT_WRITE|PROT_EXEC);
 }
 
-/*
- * Garbage collects the physical map system for pages which are
- * no longer used. Success need not be guaranteed -- that is, there
- * may well be pages which are not referenced, but others may be collected
- * Called by the pageout daemon when pages are scarce.
- */
-void
-pmap_collect(pmap_t pm)
-{
-	/* This could return unused v->p table layers which
-	 * are empty.
-	 * could malicious programs allocate memory and eat
-	 * these wired pages? These are allocated via pool.
-	 * Are there pool functions which could be called
-	 * to lower the pool usage here?
-	 */
-}
-
 /*
  * Fill the given physical page with zeros.
  */
diff --git a/sys/arch/sh/include/pmap.h b/sys/arch/sh/include/pmap.h
index 06b1c48236c..dff64bce05c 100644
--- a/sys/arch/sh/include/pmap.h
+++ b/sys/arch/sh/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.14 2015/02/15 21:34:33 miod Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.15 2022/09/10 20:35:29 miod Exp $	*/
 /*	$NetBSD: pmap.h,v 1.28 2006/04/10 23:12:11 uwe Exp $	*/
 
 /*-
@@ -64,7 +64,6 @@ void pmap_bootstrap(void);
 #define	pmap_deactivate(pmap)		do { /* nothing */ } while (0)
 #define	pmap_update(pmap)		do { /* nothing */ } while (0)
 #define	pmap_copy(dp,sp,d,l,s)		do { /* nothing */ } while (0)
-#define	pmap_collect(pmap)		do { /* nothing */ } while (0)
 #define	pmap_wired_count(pmap)		((pmap)->pm_stats.wired_count)
 #define	pmap_resident_count(pmap)	((pmap)->pm_stats.resident_count)
 
diff --git a/sys/arch/sparc64/include/pmap.h b/sys/arch/sparc64/include/pmap.h
index c07d8c46a8a..3941383f91c 100644
--- a/sys/arch/sparc64/include/pmap.h
+++ b/sys/arch/sparc64/include/pmap.h
@@ -177,6 +177,8 @@ void pmap_bootstrap(u_long, u_long, u_int, u_int);
 
 #define PMAP_GROWKERNEL         /* turn on pmap_growkernel interface */
 
+#define	__HAVE_PMAP_COLLECT
+
 /* SPARC specific? */
 void		pmap_redzone(void);
 int             pmap_dumpsize(void);
diff --git a/sys/arch/sparc64/sparc64/pmap.c b/sys/arch/sparc64/sparc64/pmap.c
index 5e5b80dd2d0..3800557252a 100644
--- a/sys/arch/sparc64/sparc64/pmap.c
+++ b/sys/arch/sparc64/sparc64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.105 2022/09/08 17:44:48 miod Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.106 2022/09/10 20:35:29 miod Exp $	*/
 /*	$NetBSD: pmap.c,v 1.107 2001/08/31 16:47:41 eeh Exp $	*/
 /*
  * 
@@ -1546,7 +1546,6 @@ pmap_copy(struct pmap *dst_pmap, struct pmap *src_pmap, vaddr_t dst_addr,
 void
 pmap_collect(struct pmap *pm)
 {
-#if 1
 	int i, j, k, n, m, s;
 	paddr_t *pdir, *ptbl;
 	/* This is a good place to scan the pmaps for page tables with
@@ -1584,7 +1583,6 @@ pmap_collect(struct pmap *pm)
 		}
 	}
 	splx(s);
-#endif
 }
 
 void
diff --git a/sys/uvm/uvm_glue.c b/sys/uvm/uvm_glue.c
index c37b24720c5..9c45bfdb767 100644
--- a/sys/uvm/uvm_glue.c
+++ b/sys/uvm/uvm_glue.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_glue.c,v 1.83 2022/03/12 08:11:07 mpi Exp $	*/
+/*	$OpenBSD: uvm_glue.c,v 1.84 2022/09/10 20:35:29 miod Exp $	*/
 /*	$NetBSD: uvm_glue.c,v 1.44 2001/02/06 19:54:44 eeh Exp $	*/
 
 /* 
@@ -321,6 +321,8 @@ uvm_init_limits(struct plimit *limit0)
 	limit0->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(uvmexp.free);
 }
 
+#ifdef __HAVE_PMAP_COLLECT
+
 #ifdef DEBUG
 int	enableswap = 1;
 int	swapdebug = 0;
@@ -414,6 +416,8 @@ next_process:	;
 	}
 }
 
+#endif	/* __HAVE_PMAP_COLLECT */
+
 /*
  * uvm_atopg: convert KVAs back to their page structures.
  */
diff --git a/sys/uvm/uvm_pdaemon.c b/sys/uvm/uvm_pdaemon.c
index 350f95edb6b..eeee53330cc 100644
--- a/sys/uvm/uvm_pdaemon.c
+++ b/sys/uvm/uvm_pdaemon.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_pdaemon.c,v 1.104 2022/08/31 09:26:04 mpi Exp $	*/
+/*	$OpenBSD: uvm_pdaemon.c,v 1.105 2022/09/10 20:35:29 miod Exp $	*/
 /*	$NetBSD: uvm_pdaemon.c,v 1.23 2000/08/20 10:24:14 bjh21 Exp $	*/
 
 /*
@@ -890,7 +890,7 @@ uvmpd_scan(struct uvm_pmalloc *pma)
 	 */
 	free = uvmexp.free - BUFPAGES_DEFICIT;
 
-#ifndef __SWAP_BROKEN
+#ifdef __HAVE_PMAP_COLLECT
 	/*
 	 * swap out some processes if we are below our free target.
 	 * we need to unlock the page queues for this.
diff --git a/sys/uvm/uvm_pmap.h b/sys/uvm/uvm_pmap.h
index e971573c5f1..88bcc0d6fdc 100644
--- a/sys/uvm/uvm_pmap.h
+++ b/sys/uvm/uvm_pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_pmap.h,v 1.30 2022/08/07 19:39:25 miod Exp $	*/
+/*	$OpenBSD: uvm_pmap.h,v 1.31 2022/09/10 20:35:29 miod Exp $	*/
 /*	$NetBSD: uvm_pmap.h,v 1.1 2000/06/27 09:00:14 mrg Exp $	*/
 
 /* 
@@ -126,7 +126,7 @@ boolean_t	 pmap_clear_modify(struct vm_page *);
 boolean_t	 pmap_clear_reference(struct vm_page *);
 #endif
 
-#if !defined(pmap_collect)
+#if !defined(pmap_collect) && defined(__HAVE_PMAP_COLLECT)
 void		 pmap_collect(pmap_t);
 #endif
 #if !defined(pmap_copy)
-- 
2.20.1