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Fixed bug related to proper sensing of page modification that we

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inadvertantly introduced in pre-1.1.5. This could cause page modifications
to go unnoticed during certain extreme low memory/high paging rate conditions.

Submitted by:	John Dyson and David Greenman
This commit is contained in:
David Greenman 1994-10-04 03:05:09 +00:00
parent b3760f248a
commit edaaafdb0f
1 changed files with 9 additions and 8 deletions
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17
sys/vm/vm_pageout.c
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@ -65,7 +65,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_pageout.c,v 1.11 1994/09/12 11:31:36 davidg Exp $
* $Id: vm_pageout.c,v 1.12 1994/09/12 15:06:14 davidg Exp $
*/
/*
@ -646,15 +646,16 @@ vm_pageout_scan()
}
/*
* if page is clean and but the page has been referenced,
* then reactivate the page, but if we are very low on memory
* or the page has not been referenced, then we free it to the
* vm system.
* NOTE: PG_CLEAN doesn't guarantee that the page is clean.
*/
if (m->flags & PG_CLEAN) {
if ((cnt.v_free_count > vm_pageout_free_min) /* XXX */
&& ((pmap_is_referenced(VM_PAGE_TO_PHYS(m)) ||
(m->flags & PG_REFERENCED) != 0))) {
/*
* If we're not low on memory and the page has been reference,
* or if the page has been modified, then reactivate the page.
*/
if (((cnt.v_free_count > vm_pageout_free_min) &&
(pmap_is_referenced(VM_PAGE_TO_PHYS(m)) || ((m->flags & PG_REFERENCED) != 0))) ||
pmap_is_modified(VM_PAGE_TO_PHYS(m))) {
m->flags &= ~PG_REFERENCED;
vm_page_activate(m);
} else if (!m->act_count) {