K 10
svn:author
V 3
alc
K 8
svn:date
V 27
2004-12-13T06:24:14.000000Z
K 7
svn:log
V 626
Correct the handling of two unusual cases by the zero-copy receive path,
specifically, vm_pgmoveco():
1. If vm_pgmoveco() sleeps on a busy page, it must redo the look up
because the page may have been freed.
2. If the receive buffer is copy-on-write due to, for example, a fork,
then although the first vm object in the shadow chain may not contain
a page there may still be one from a backing object that is mapped.
Thus, a pmap_remove() is required for the new page rather than the
backing object's page to been seen by the application.

Also, add some comments to vm_pgmoveco() and update some assertions.

Tested by: ken@

END