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Transfer responsibility for freeing the page taken from the cache

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queue and (possibly) unlocking the containing object from
vm_page_alloc() to vm_page_select_cache().  Recent optimizations to
vm_map_pmap_enter() (see vm_map.c revisions 1.362 and 1.363) and
pmap_enter_quick() have resulted in panic()s because vm_page_alloc()
mistakenly unlocked objects that had not been locked by
vm_page_select_cache().

Reported by: Peter Holm and Kris Kennaway
This commit is contained in:
Alan Cox 2005-01-07 05:02:19 +00:00
parent 45a0fd86e1
commit 46fbc58202
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=139835
1 changed files with 17 additions and 19 deletions
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36
sys/vm/vm_page.c
View File

@ -693,31 +693,35 @@ vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex)
/*
* vm_page_select_cache:
*
* Find a page on the cache queue with color optimization. As pages
* might be found, but not applicable, they are deactivated. This
* keeps us from using potentially busy cached pages.
* Move a page of the given color from the cache queue to the free
* queue. As pages might be found, but are not applicable, they are
* deactivated.
*
* This routine may not block.
*/
vm_page_t
vm_page_select_cache(int color)
{
vm_object_t object;
vm_page_t m;
boolean_t was_trylocked;
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
while ((m = vm_pageq_find(PQ_CACHE, color, FALSE)) != NULL) {
if (m->hold_count == 0 && (VM_OBJECT_TRYLOCK(m->object) ||
VM_OBJECT_LOCKED(m->object))) {
KASSERT(m->dirty == 0, ("Found dirty cache page %p", m));
KASSERT(!pmap_page_is_mapped(m),
("Found mapped cache page %p", m));
KASSERT((m->flags & PG_UNMANAGED) == 0,
("Found unmanaged cache page %p", m));
KASSERT(m->wire_count == 0, ("Found wired cache page %p", m));
if (m->hold_count == 0 && (object = m->object,
(was_trylocked = VM_OBJECT_TRYLOCK(object)) ||
VM_OBJECT_LOCKED(object))) {
KASSERT((m->flags & PG_BUSY) == 0 && m->busy == 0,
("Found busy cache page %p", m));
KASSERT(m->dirty == 0,
("Found dirty cache page %p", m));
KASSERT(!pmap_page_is_mapped(m),
("Found mapped cache page %p", m));
KASSERT((m->flags & PG_UNMANAGED) == 0,
("Found unmanaged cache page %p", m));
KASSERT(m->wire_count == 0,
("Found wired cache page %p", m));
vm_page_free(m);
if (was_trylocked)
VM_OBJECT_UNLOCK(object);
break;
}
vm_page_deactivate(m);
@ -746,7 +750,6 @@ vm_page_select_cache(int color)
vm_page_t
vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
{
vm_object_t m_object;
vm_page_t m = NULL;
int color, flags, page_req;
@ -800,12 +803,7 @@ vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
pagedaemon_wakeup();
return (NULL);
}
m_object = m->object;
VM_OBJECT_LOCK_ASSERT(m_object, MA_OWNED);
vm_page_free(m);
vm_page_unlock_queues();
if (m_object != object)
VM_OBJECT_UNLOCK(m_object);
goto loop;
} else {
/*