K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2020-01-24T19:42:53.366163Z
K 7
svn:log
V 406
Handle a race of collapse with a retrying fault.

Both vm_object_scan_all_shadowed() and vm_object_collapse_scan() might
observe an invalid page left in the default backing object by the
fault handler that retried.  Check for the condition and refuse to collapse.

Reported and tested by:	pho
Reviewed by:	jeff
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D23331

END