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PR 40027/pagedaemon loops on memory shortage

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uvmpd_scan_queue:

- Fix a bug that prevented the pagedaemon from making forward progress
  if (a) swap was full (b) the first 16 pages on the inactive list were
  unbusy anons not already backed by swap.

- Remove redundant uvm_swapisfull() check and just try to allocate a slot.
  If it fails we know swap is full.
This commit is contained in:
ad 2008-12-13 11:26:57 +00:00
parent f9a4aaf41f
commit 9d315c5bc9
1 changed files with 12 additions and 22 deletions
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34
sys/uvm/uvm_pdaemon.c
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@ -1,4 +1,4 @@
/* $NetBSD: uvm_pdaemon.c,v 1.96 2008/12/03 11:43:51 ad Exp $ */
/* $NetBSD: uvm_pdaemon.c,v 1.97 2008/12/13 11:26:57 ad Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
@ -71,7 +71,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.96 2008/12/03 11:43:51 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.97 2008/12/13 11:26:57 ad Exp $");
#include "opt_uvmhist.h"
#include "opt_readahead.h"
@ -294,20 +294,20 @@ uvm_pageout(void *arg)
needsfree = uvmexp.free + uvmexp.paging < uvmexp.freetarg;
needsscan = needsfree || uvmpdpol_needsscan_p();
mutex_spin_exit(&uvm_fpageqlock);
/*
* scan if needed
*/
if (needsscan)
if (needsscan) {
mutex_spin_exit(&uvm_fpageqlock);
uvmpd_scan();
mutex_spin_enter(&uvm_fpageqlock);
}
/*
* if there's any free memory to be had,
* wake up any waiters.
*/
mutex_spin_enter(&uvm_fpageqlock);
if (uvmexp.free > uvmexp.reserve_kernel ||
uvmexp.paging == 0) {
wakeup(&uvmexp.free);
@ -849,28 +849,18 @@ uvmpd_scan_queue(void)
uvmpd_dropswap(p);
/*
* if all pages in swap are only in swap,
* the swap space is full and we can't page out
* any more swap-backed pages. reactivate this page
* so that we eventually cycle all pages through
* the inactive queue.
*/
if (uvm_swapisfull()) {
dirtyreacts++;
uvm_pageactivate(p);
mutex_exit(slock);
continue;
}
/*
* start new swap pageout cluster (if necessary).
*
* if swap is full reactivate this page so that
* we eventually cycle all pages through the
* inactive queue.
*/
if (swapcluster_allocslots(&swc)) {
dirtyreacts++;
uvm_pageactivate(p);
mutex_exit(slock);
dirtyreacts++; /* XXX */
continue;
}