static int
ulz_put(struct uvm_object *uobj, voff_t start, voff_t stop, int flags)
{
struct vm_page *pg;
KDASSERT(uobj == &uvm_loanzero_object);
/*
* Don't need to do any work here if we're not freeing pages.
*/
if ((flags & PGO_FREE) == 0) {
mutex_exit(&uobj->vmobjlock);
return 0;
}
/*
* we don't actually want to ever free the uvm_loanzero_page, so
* just reactivate or dequeue it.
*/
pg = TAILQ_FIRST(&uobj->memq);
KASSERT(pg != NULL);
KASSERT(TAILQ_NEXT(pg, listq.queue) == NULL);
mutex_enter(&uvm_pageqlock);
if (pg->uanon)
uvm_pageactivate(pg);
else
uvm_pagedequeue(pg);
mutex_exit(&uvm_pageqlock);
mutex_exit(&uobj->vmobjlock);
return 0;
}
int
uvm_loanbreak_anon(struct vm_anon *anon, struct uvm_object *uobj)
{
struct vm_page *pg;
KASSERT(mutex_owned(anon->an_lock));
KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock));
/* get new un-owned replacement page */
pg = uvm_pagealloc(NULL, 0, NULL, 0);
if (pg == NULL) {
return ENOMEM;
}
/* copy old -> new */
uvm_pagecopy(anon->an_page, pg);
/* force reload */
pmap_page_protect(anon->an_page, VM_PROT_NONE);
mutex_enter(&uvm_pageqlock); /* KILL loan */
anon->an_page->uanon = NULL;
/* in case we owned */
anon->an_page->pqflags &= ~PQ_ANON;
if (uobj) {
/* if we were receiver of loan */
anon->an_page->loan_count--;
} else {
/*
* we were the lender (A->K); need to remove the page from
* pageq's.
*/
uvm_pagedequeue(anon->an_page);
}
if (uobj) {
mutex_exit(uobj->vmobjlock);
}
/* install new page in anon */
anon->an_page = pg;
pg->uanon = anon;
pg->pqflags |= PQ_ANON;
uvm_pageactivate(pg);
mutex_exit(&uvm_pageqlock);
pg->flags &= ~(PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
/* done! */
return 0;
}
/*
* uvm_loanbreak: break loan on a uobj page
*
* => called with uobj locked
* => the page should be busy
* => return value:
* newly allocated page if succeeded
*/
struct vm_page *
uvm_loanbreak(struct vm_page *uobjpage)
{
struct vm_page *pg;
#ifdef DIAGNOSTIC
struct uvm_object *uobj = uobjpage->uobject;
#endif
KASSERT(uobj != NULL);
KASSERT(mutex_owned(&uobj->vmobjlock));
KASSERT(uobjpage->flags & PG_BUSY);
/* alloc new un-owned page */
pg = uvm_pagealloc(NULL, 0, NULL, 0);
if (pg == NULL)
return NULL;
/*
* copy the data from the old page to the new
* one and clear the fake flags on the new page (keep it busy).
* force a reload of the old page by clearing it from all
* pmaps.
* transfer dirtiness of the old page to the new page.
* then lock the page queues to rename the pages.
*/
uvm_pagecopy(uobjpage, pg); /* old -> new */
pg->flags &= ~PG_FAKE;
pmap_page_protect(uobjpage, VM_PROT_NONE);
if ((uobjpage->flags & PG_CLEAN) != 0 && !pmap_clear_modify(uobjpage)) {
pmap_clear_modify(pg);
pg->flags |= PG_CLEAN;
} else {
/* uvm_pagecopy marked it dirty */
KASSERT((pg->flags & PG_CLEAN) == 0);
/* a object with a dirty page should be dirty. */
KASSERT(!UVM_OBJ_IS_CLEAN(uobj));
}
if (uobjpage->flags & PG_WANTED)
wakeup(uobjpage);
/* uobj still locked */
uobjpage->flags &= ~(PG_WANTED|PG_BUSY);
UVM_PAGE_OWN(uobjpage, NULL);
mutex_enter(&uvm_pageqlock);
/*
* replace uobjpage with new page.
*/
uvm_pagereplace(uobjpage, pg);
/*
* if the page is no longer referenced by
* an anon (i.e. we are breaking an O->K
* loan), then remove it from any pageq's.
*/
if (uobjpage->uanon == NULL)
uvm_pagedequeue(uobjpage);
/*
* at this point we have absolutely no
* control over uobjpage
*/
/* install new page */
uvm_pageactivate(pg);
mutex_exit(&uvm_pageqlock);
/*
* done! loan is broken and "pg" is
* PG_BUSY. it can now replace uobjpage.
*/
return pg;
}
