K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2018-03-26T16:31:12.123203Z
K 7
svn:log
V 875
Allow to specify for vm_fault_quick_hold_pages() that nofault mode
should be honored.

We must not sleep or acquire any MI VM locks if TDP_NOFAULTING is
specified.  On the other hand, there were some callers in the tree
which set TDP_NOFAULTING for larger scope than needed, I fixed the
code which I wrote, but I suspect that linuxkpi and out of tree drm
drivers might abuse this still.

So only enable the mode for vm_fault_quick_hold_pages() where
vm_fault_hold() is not called when specifically asked by user.  I
decided to use vm_prot_t flag to not change KPI.  Since number of
flags in vm_prot_t is limited, I reused the same flag which was
already consumed for vm_map_lookup().

Reported and tested by:	pho (as part of the larger patch)
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D14825

END