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Previously, nothing prevented the page that was returned by pmap_extract()

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from being reclaimed before it was wired.  Use pmap_extract_and_hold()
instead of pmap_extract() and retain the hold on the page until it has been
wired.
This commit is contained in:
Alan Cox 2005-10-23 07:41:56 +00:00
parent ce887d5191
commit 5b5908005a
1 changed files with 3 additions and 4 deletions
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7
sys/kern/uipc_cow.c
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@ -99,7 +99,6 @@ socow_setup(struct mbuf *m0, struct uio *uio)
{
struct sf_buf *sf;
vm_page_t pp;
vm_paddr_t pa;
struct iovec *iov;
struct vmspace *vmspace;
struct vm_map *map;
@ -120,12 +119,11 @@ socow_setup(struct mbuf *m0, struct uio *uio)
/*
* verify page is mapped & not already wired for i/o
*/
pa=pmap_extract(map->pmap, uva);
if(!pa) {
pp = pmap_extract_and_hold(map->pmap, uva, VM_PROT_READ);
if (pp == NULL) {
socow_stats.fail_not_mapped++;
return(0);
}
pp = PHYS_TO_VM_PAGE(pa);
/*
* set up COW
@ -137,6 +135,7 @@ socow_setup(struct mbuf *m0, struct uio *uio)
* wire the page for I/O
*/
vm_page_wire(pp);
vm_page_unhold(pp);
vm_page_unlock_queues();
/*