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Implemented swap locking via P_SWAPPING flag. It was possible for a process

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to be chosen for swap-in while it was being swapped-out. This was BAD.

Submitted by:	John Dyson
This commit is contained in:
David Greenman 1994-11-13 12:47:07 +00:00
parent 0d15e0ac1e
commit bfbfac11c9
1 changed files with 11 additions and 5 deletions
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16
sys/vm/vm_glue.c
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@ -59,7 +59,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_glue.c,v 1.7 1994/09/12 15:06:12 davidg Exp $
* $Id: vm_glue.c,v 1.8 1994/10/09 01:52:08 phk Exp $
*/
#include <sys/param.h>
@ -397,7 +397,7 @@ scheduler()
pp = NULL;
ppri = INT_MIN;
for (p = (struct proc *)allproc; p != NULL; p = p->p_next) {
if (p->p_stat == SRUN && (p->p_flag & P_INMEM) == 0) {
if (p->p_stat == SRUN && (p->p_flag & (P_INMEM|P_SWAPPING)) == 0) {
int mempri;
pri = p->p_swtime + p->p_slptime - p->p_nice * 8;
mempri = pri > 0 ? pri : 0;
@ -461,7 +461,7 @@ scheduler()
#define swappable(p) \
(((p)->p_lock == 0) && \
((p)->p_flag & (P_TRACED|P_NOSWAP|P_SYSTEM|P_INMEM|P_WEXIT|P_PHYSIO)) == P_INMEM)
((p)->p_flag & (P_TRACED|P_NOSWAP|P_SYSTEM|P_INMEM|P_WEXIT|P_PHYSIO|P_SWAPPING)) == P_INMEM)
extern int vm_pageout_free_min;
/*
@ -504,6 +504,12 @@ swapout_threads()
case SSLEEP:
case SSTOP:
/*
* do not swapout a realtime process
*/
if (p->p_rtprio.type == RTP_PRIO_REALTIME)
continue;
/*
* do not swapout a process that is waiting for VM datastructures
* there is a possible deadlock.
@ -590,7 +596,7 @@ swapout(p)
remrq(p);
(void) spl0();
++p->p_lock;
p->p_flag |= P_SWAPPING;
/* let the upages be paged */
pmap_remove(vm_map_pmap(kernel_map),
(vm_offset_t) p->p_addr, ((vm_offset_t) p->p_addr) + UPAGES * NBPG);
@ -598,7 +604,7 @@ swapout(p)
vm_map_pageable(map, (vm_offset_t) kstack,
(vm_offset_t) kstack + UPAGES * NBPG, TRUE);
--p->p_lock;
p->p_flag &= ~P_SWAPPING;
p->p_swtime = 0;
}