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Closed a very narrow and rare race condition that involved net interrupts,

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bio interrupts, and a truncated file that along with the precise alignment
of the planets could result in a page being freed multiple times or a
just-freed page being put onto the inactive queue.
This commit is contained in:
David Greenman 1998-11-18 09:00:47 +00:00
parent 8ea9416c8c
commit 4f699173cb
2 changed files with 8 additions and 3 deletions
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5
sys/kern/uipc_syscalls.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* @(#)uipc_syscalls.c 8.4 (Berkeley) 2/21/94
* $Id: uipc_syscalls.c,v 1.44 1998/11/14 23:36:17 dg Exp $
* $Id: uipc_syscalls.c,v 1.45 1998/11/15 16:55:09 dg Exp $
*/
#include "opt_compat.h"
@ -1366,6 +1366,7 @@ sf_buf_free(caddr_t addr, u_int size)
{
struct sf_buf *sf;
struct vm_page *m;
int s;
sf = dtosf(addr);
if (sf->refcnt == 0)
@ -1374,6 +1375,7 @@ sf_buf_free(caddr_t addr, u_int size)
if (sf->refcnt == 0) {
pmap_qremove((vm_offset_t)addr, 1);
m = sf->m;
s = splvm();
vm_page_unwire(m, 0);
/*
* Check for the object going away on us. This can
@ -1382,6 +1384,7 @@ sf_buf_free(caddr_t addr, u_int size)
*/
if (m->wire_count == 0 && m->object == NULL)
vm_page_free(m);
splx(s);
sf->m = NULL;
SLIST_INSERT_HEAD(&sf_freelist, sf, free_list);
if (sf_buf_alloc_want) {

6
sys/kern/vfs_bio.c
View File

@ -11,7 +11,7 @@
* 2. Absolutely no warranty of function or purpose is made by the author
* John S. Dyson.
*
* $Id: vfs_bio.c,v 1.183 1998/10/30 14:53:54 dg Exp $
* $Id: vfs_bio.c,v 1.184 1998/10/31 15:31:22 peter Exp $
*/
/*
@ -788,9 +788,10 @@ static void
vfs_vmio_release(bp)
struct buf *bp;
{
int i;
int i, s;
vm_page_t m;
s = splvm();
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
bp->b_pages[i] = NULL;
@ -820,6 +821,7 @@ vfs_vmio_release(bp)
}
}
}
splx(s);
bufspace -= bp->b_bufsize;
vmiospace -= bp->b_bufsize;
pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);