[src/trunk]: src/sys/uvm Don't call uvm_pagedequeue() while holding pg->inter...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/632cdd64dce1
branches:  trunk
changeset: 847187:632cdd64dce1
user:      ad <ad%NetBSD.org@localhost>
date:      Sat Dec 14 15:08:45 2019 +0000

description:
Don't call uvm_pagedequeue() while holding pg->interlock.

diffstat:

 sys/uvm/uvm_loan.c |  14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diffs (68 lines):

diff -r 8323b6f9ded1 -r 632cdd64dce1 sys/uvm/uvm_loan.c
--- a/sys/uvm/uvm_loan.c        Sat Dec 14 15:04:47 2019 +0000
+++ b/sys/uvm/uvm_loan.c        Sat Dec 14 15:08:45 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_loan.c,v 1.89 2019/12/13 20:10:22 ad Exp $ */
+/*     $NetBSD: uvm_loan.c,v 1.90 2019/12/14 15:08:45 ad Exp $ */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_loan.c,v 1.89 2019/12/13 20:10:22 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_loan.c,v 1.90 2019/12/14 15:08:45 ad Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -1149,6 +1149,7 @@
 
        mutex_enter(&uobjpage->interlock);
        uvm_pagereplace(uobjpage, pg);
+       mutex_exit(&uobjpage->interlock);
 
        /*
         * if the page is no longer referenced by
@@ -1157,7 +1158,6 @@
         */
        if (uobjpage->uanon == NULL)
                uvm_pagedequeue(uobjpage);
-       mutex_exit(&uobjpage->interlock);
 
        /*
         * at this point we have absolutely no
@@ -1177,7 +1177,7 @@
 int
 uvm_loanbreak_anon(struct vm_anon *anon, struct uvm_object *uobj)
 {
-       struct vm_page *pg;
+       struct vm_page *pg, *dequeuepg;
 
        KASSERT(mutex_owned(anon->an_lock));
        KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock));
@@ -1207,12 +1207,13 @@
        if (uobj) {
                /* if we were receiver of loan */
                anon->an_page->loan_count--;
+               dequeuepg = NULL;
        } else {
                /*
                 * we were the lender (A->K); need to remove the page from
                 * pageq's.
                 */
-               uvm_pagedequeue(anon->an_page);
+               dequeuepg = anon->an_page;
        }
 
        /* install new page in anon */
@@ -1223,6 +1224,9 @@
        mutex_exit(&pg->interlock);
        mutex_exit(&anon->an_page->interlock);
        uvm_pageactivate(pg);
+       if (dequeuepg != NULL) {
+               uvm_pagedequeue(anon->an_page);
+       }
 
        pg->flags &= ~(PG_BUSY|PG_FAKE);
        UVM_PAGE_OWN(pg, NULL);