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Change vm_page_cache_transfer() such that it does not transfer pages

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that would have an offset beyond the end of the target object.  Such
pages should remain in the source object.

MFC after:	3 days
Diagnosed and reviewed by:	Kostik Belousov
Reported and tested by:		Peter Holm
This commit is contained in:
Alan Cox 2007-10-27 00:09:30 +00:00
parent 6bc3d1dc09
commit 21f7958604
1 changed files with 20 additions and 10 deletions
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30
sys/vm/vm_page.c
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@ -916,7 +916,9 @@ vm_page_cache_remove(vm_page_t m)
/*
* Transfer all of the cached pages with offset greater than or
* equal to 'offidxstart' from the original object's cache to the
* new object's cache. Initially, the new object's cache must be
* new object's cache. However, any cached pages with offset
* greater than or equal to the new object's size are kept in the
* original object. Initially, the new object's cache must be
* empty. Offset 'offidxstart' in the original object must
* correspond to offset zero in the new object.
*
@ -954,17 +956,21 @@ vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart,
new_object->cache = m;
m->left = NULL;
}
KASSERT(new_object->cache == NULL ||
new_object->type == OBJT_SWAP,
("vm_page_cache_transfer: object %p's type is incompatible"
" with cached pages", new_object));
/*
* Update the object and offset of each page that was
* transferred to the new object's cache.
*/
while ((m = new_object->cache) != NULL) {
if ((m->pindex - offidxstart) >= new_object->size) {
/*
* Return all of the cached pages with
* offset greater than or equal to the
* new object's size to the original
* object's cache.
*/
new_object->cache = m->left;
m->left = orig_object->cache;
orig_object->cache = m;
break;
}
m_next = vm_page_splay(m->pindex, m->right);
/* Update the page's object and offset. */
m->object = new_object;
m->pindex -= offidxstart;
if (m_next == NULL)
@ -973,6 +979,10 @@ vm_page_cache_transfer(vm_object_t orig_object, vm_pindex_t offidxstart,
m_next->left = m;
new_object->cache = m_next;
}
KASSERT(new_object->cache == NULL ||
new_object->type == OBJT_SWAP,
("vm_page_cache_transfer: object %p's type is incompatible"
" with cached pages", new_object));
}
mtx_unlock(&vm_page_queue_free_mtx);
}