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Use of the ZERO_COPY_SOCKETS options can result in an unusual state that

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vm_object_backing_scan() was not written to handle.  Specifically, a wired
page within a backing object that is shadowed by a page within the shadow
object.  Handle this state by removing the wired page from the backing
object.  The wired page will be freed by socow_iodone().

Stop masking errors: If a page is being freed by vm_object_backing_scan(),
assert that it is no longer mapped rather than quietly destroying any
mappings.

Tested by: Harald Schmalzbauer
This commit is contained in:
alc 2005-10-22 18:46:38 +00:00
parent cdb10bb44d
commit 80f50568e4
1 changed files with 12 additions and 4 deletions
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16
sys/vm/vm_object.c
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@ -1493,8 +1493,12 @@ vm_object_backing_scan(vm_object_t object, int op)
* can simply destroy it.
*/
vm_page_lock_queues();
pmap_remove_all(p);
vm_page_free(p);
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (p->wire_count == 0)
vm_page_free(p);
else
vm_page_remove(p);
vm_page_unlock_queues();
p = next;
continue;
@ -1513,8 +1517,12 @@ vm_object_backing_scan(vm_object_t object, int op)
* Leave the parent's page alone
*/
vm_page_lock_queues();
pmap_remove_all(p);
vm_page_free(p);
KASSERT(!pmap_page_is_mapped(p),
("freeing mapped page %p", p));
if (p->wire_count == 0)
vm_page_free(p);
else
vm_page_remove(p);
vm_page_unlock_queues();
p = next;
continue;