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Date:      Wed, 28 Aug 2019 16:16:14 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r351570 - stable/12/sys/vm
Message-ID:  <201908281616.x7SGGEmB020592@repo.freebsd.org>
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Author: markj
Date: Wed Aug 28 16:16:14 2019
New Revision: 351570
URL: https://svnweb.freebsd.org/changeset/base/351570

Log:
  MFC r351333:
  Simplify vm_page_dequeue() and fix an assertion.

Modified:
  stable/12/sys/vm/vm_page.c
  stable/12/sys/vm/vm_page.h
  stable/12/sys/vm/vm_pagequeue.h
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/vm/vm_page.c
==============================================================================
--- stable/12/sys/vm/vm_page.c	Wed Aug 28 16:08:06 2019	(r351569)
+++ stable/12/sys/vm/vm_page.c	Wed Aug 28 16:16:14 2019	(r351570)
@@ -3079,21 +3079,15 @@ vm_waitpfault(struct domainset *dset)
 		mtx_unlock(&vm_domainset_lock);
 }
 
-struct vm_pagequeue *
+static struct vm_pagequeue *
 vm_page_pagequeue(vm_page_t m)
 {
 
-	return (&vm_pagequeue_domain(m)->vmd_pagequeues[m->queue]);
-}
-
-static struct mtx *
-vm_page_pagequeue_lockptr(vm_page_t m)
-{
 	uint8_t queue;
 
 	if ((queue = atomic_load_8(&m->queue)) == PQ_NONE)
 		return (NULL);
-	return (&vm_pagequeue_domain(m)->vmd_pagequeues[queue].pq_mutex);
+	return (&vm_pagequeue_domain(m)->vmd_pagequeues[queue]);
 }
 
 static inline void
@@ -3116,10 +3110,8 @@ vm_pqbatch_process_page(struct vm_pagequeue *pq, vm_pa
 	    m, pq, qflags));
 
 	if ((qflags & PGA_DEQUEUE) != 0) {
-		if (__predict_true((qflags & PGA_ENQUEUED) != 0)) {
-			TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
-			vm_pagequeue_cnt_dec(pq);
-		}
+		if (__predict_true((qflags & PGA_ENQUEUED) != 0))
+			vm_pagequeue_remove(pq, m);
 		vm_page_dequeue_complete(m);
 	} else if ((qflags & (PGA_REQUEUE | PGA_REQUEUE_HEAD)) != 0) {
 		if ((qflags & PGA_ENQUEUED) != 0)
@@ -3293,16 +3285,14 @@ vm_page_dequeue_deferred(vm_page_t m)
 void
 vm_page_dequeue(vm_page_t m)
 {
-	struct mtx *lock, *lock1;
-	struct vm_pagequeue *pq;
+	struct vm_pagequeue *pq, *pq1;
 	uint8_t aflags;
 
-	KASSERT(mtx_owned(vm_page_lockptr(m)) || m->order == VM_NFREEORDER,
+	KASSERT(mtx_owned(vm_page_lockptr(m)) || m->object == NULL,
 	    ("page %p is allocated and unlocked", m));
 
-	for (;;) {
-		lock = vm_page_pagequeue_lockptr(m);
-		if (lock == NULL) {
+	for (pq = vm_page_pagequeue(m);; pq = pq1) {
+		if (pq == NULL) {
 			/*
 			 * A thread may be concurrently executing
 			 * vm_page_dequeue_complete().  Ensure that all queue
@@ -3321,27 +3311,24 @@ vm_page_dequeue(vm_page_t m)
 			 * critical section.
 			 */
 			cpu_spinwait();
+			pq1 = vm_page_pagequeue(m);
 			continue;
 		}
-		mtx_lock(lock);
-		if ((lock1 = vm_page_pagequeue_lockptr(m)) == lock)
+		vm_pagequeue_lock(pq);
+		if ((pq1 = vm_page_pagequeue(m)) == pq)
 			break;
-		mtx_unlock(lock);
-		lock = lock1;
+		vm_pagequeue_unlock(pq);
 	}
-	KASSERT(lock == vm_page_pagequeue_lockptr(m),
+	KASSERT(pq == vm_page_pagequeue(m),
 	    ("%s: page %p migrated directly between queues", __func__, m));
 	KASSERT((m->aflags & PGA_DEQUEUE) != 0 ||
 	    mtx_owned(vm_page_lockptr(m)),
 	    ("%s: queued unlocked page %p", __func__, m));
 
-	if ((m->aflags & PGA_ENQUEUED) != 0) {
-		pq = vm_page_pagequeue(m);
-		TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
-		vm_pagequeue_cnt_dec(pq);
-	}
+	if ((m->aflags & PGA_ENQUEUED) != 0)
+		vm_pagequeue_remove(pq, m);
 	vm_page_dequeue_complete(m);
-	mtx_unlock(lock);
+	vm_pagequeue_unlock(pq);
 }
 
 /*

Modified: stable/12/sys/vm/vm_page.h
==============================================================================
--- stable/12/sys/vm/vm_page.h	Wed Aug 28 16:08:06 2019	(r351569)
+++ stable/12/sys/vm/vm_page.h	Wed Aug 28 16:16:14 2019	(r351570)
@@ -554,7 +554,6 @@ void vm_page_launder(vm_page_t m);
 vm_page_t vm_page_lookup (vm_object_t, vm_pindex_t);
 vm_page_t vm_page_next(vm_page_t m);
 int vm_page_pa_tryrelock(pmap_t, vm_paddr_t, vm_paddr_t *);
-struct vm_pagequeue *vm_page_pagequeue(vm_page_t m);
 vm_page_t vm_page_prev(vm_page_t m);
 bool vm_page_ps_test(vm_page_t m, int flags, vm_page_t skip_m);
 void vm_page_putfake(vm_page_t m);

Modified: stable/12/sys/vm/vm_pagequeue.h
==============================================================================
--- stable/12/sys/vm/vm_pagequeue.h	Wed Aug 28 16:08:06 2019	(r351569)
+++ stable/12/sys/vm/vm_pagequeue.h	Wed Aug 28 16:16:14 2019	(r351570)
@@ -199,6 +199,14 @@ vm_pagequeue_cnt_add(struct vm_pagequeue *pq, int adde
 #define	vm_pagequeue_cnt_dec(pq)	vm_pagequeue_cnt_add((pq), -1)
 
 static inline void
+vm_pagequeue_remove(struct vm_pagequeue *pq, vm_page_t m)
+{
+
+	TAILQ_REMOVE(&pq->pq_pl, m, plinks.q);
+	vm_pagequeue_cnt_dec(pq);
+}
+
+static inline void
 vm_batchqueue_init(struct vm_batchqueue *bq)
 {

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