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when wiring swap-backed pages, clear the PG_CLEAN flag before

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releasing any swap resources.  if we don't do this, we can
end up with a clean, swap-backed page, which is illegal.
tracked down by Bill Sommerfeld, fixes PR 7578.
This commit is contained in:
chs 1999-05-19 06:14:15 +00:00
parent 662828c4ce
commit a5d3e8dae9
1 changed files with 19 additions and 4 deletions
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23
sys/uvm/uvm_fault.c
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@ -1,4 +1,4 @@
/* $NetBSD: uvm_fault.c,v 1.28 1999/04/11 04:04:11 chs Exp $ */
/* $NetBSD: uvm_fault.c,v 1.29 1999/05/19 06:14:15 chs Exp $ */
/*
*
@ -1214,11 +1214,19 @@ ReFault:
if (fault_type == VM_FAULT_WIRE) {
uvm_pagewire(pg);
/*
* since the now-wired page cannot be paged out,
* release its swap resources for others to use.
* since an anon with no swap cannot be PG_CLEAN,
* clear its clean flag now.
*/
pg->flags &= ~(PG_CLEAN);
uvm_anon_dropswap(anon);
} else {
/* activate it */
uvm_pageactivate(pg);
}
uvm_unlock_pageq();
@ -1638,13 +1646,20 @@ Case2:
if (fault_type == VM_FAULT_WIRE) {
uvm_pagewire(pg);
if (pg->pqflags & PQ_AOBJ) {
/*
* since the now-wired page cannot be paged out,
* release its swap resources for others to use.
* since an aobj page with no swap cannot be PG_CLEAN,
* clear its clean flag now.
*/
pg->flags &= ~(PG_CLEAN);
uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
}
} else {
/* activate it */
uvm_pageactivate(pg);
}
uvm_unlock_pageq();