CVS commit: [netbsd-9] src/sys/uvm

["Martin Husemann" <martin%netbsd.org@localhost>]

Module Name:    src
Committed By:   martin
Date:           Sun Oct  4 18:14:13 UTC 2020

Modified Files:
        src/sys/uvm [netbsd-9]: uvm_amap.c uvm_io.c

Log Message:
Pull up following revision(s) (requested by chs in ticket #1095):

        sys/uvm/uvm_amap.c: revision 1.124 (via patch)
        sys/uvm/uvm_amap.c: revision 1.125 (via patch)
        sys/uvm/uvm_io.c: revision 1.29 (via patch)

Effectively disable the AMAP_REFALL flag because it is unsafe.

This flag tells the amap code that it does not need to allocate ppref
as part of adding or removing a reference, but that is only correct
if the range of the reference being added or removed is the same
as the range of all other references to the amap, and the point of
this flag is exactly to try to optimize the case where the range is
different and thus this flag would not be correct to use.
Fixes PR 55366.

The previous fix for PR 55366 in uvm_amap.c 1.124 was incomplete:
 - amap_adjref_anons() must also ignore AMAP_REFALL when updating
   the ppref, not just when deciding whether or not to initialize ppref.
 - UVM_EXTRACT_QREF relies on AMAP_REFALL to work properly,
   and since we can't use AMAP_REFALL then we can't use QREF either.


To generate a diff of this commit:
cvs rdiff -u -r1.109.4.1 -r1.109.4.2 src/sys/uvm/uvm_amap.c
cvs rdiff -u -r1.28 -r1.28.22.1 src/sys/uvm/uvm_io.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.