NetBSD Problem Report #55094

From ad@netbsd.org  Sat Mar 21 17:09:57 2020
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Date: Sat, 21 Mar 2020 17:09:57 +0000 (UTC)
From: ad@netbsd.org
Reply-To: ad@netbsd.org
To: gnats-bugs@NetBSD.org
Subject: vax pmap needs locking adjustments
X-Send-Pr-Version: 3.95

>Number:         55094
>Category:       port-vax
>Synopsis:       vax pmap needs locking adjustments
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    ad
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Mar 21 17:10:00 +0000 2020
>Closed-Date:    Sat Mar 21 18:48:39 +0000 2020
>Last-Modified:  Sat Mar 21 18:50:03 +0000 2020
>Originator:     Andrew Doran
>Release:        NetBSD 9.99.50
>Organization:
	The NetBSD Project
>Environment:
n/a
>Description:
	The vax pmap looks like it needs locking at the pmap level, to
	protect against multi-threaded programs doing concurrent operations.
	It probably works OK for pmap_kernel since there is PV list locking,
	and you don't tend to get concurrent modifications to the same VA in
	pmap_kernel.
>How-To-Repeat:
	Code inspection.
>Fix:
	Have a global pmap_lock.  That would allow removal of the atomics
	adjusting stats, and removal of pvtable_lock.  Low maintainence
	overhead and low runtime cost.

>Release-Note:

>Audit-Trail:

Responsible-Changed-From-To: port-vax-maintainer->ad
Responsible-Changed-By: ad@NetBSD.org
Responsible-Changed-When: Sat, 21 Mar 2020 17:10:55 +0000
Responsible-Changed-Why:
I like DEC equipment


State-Changed-From-To: open->closed
State-Changed-By: ad@NetBSD.org
State-Changed-When: Sat, 21 Mar 2020 18:48:39 +0000
State-Changed-Why:
fixed


From: "Andrew Doran" <ad@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/55094 CVS commit: src/sys/arch/vax
Date: Sat, 21 Mar 2020 18:47:55 +0000

 Module Name:	src
 Committed By:	ad
 Date:		Sat Mar 21 18:47:54 UTC 2020

 Modified Files:
 	src/sys/arch/vax/include: pmap.h
 	src/sys/arch/vax/vax: pmap.c

 Log Message:
 PR port-vax/55094: vax pmap needs locking adjustments

 Make the adjustments noted in the PR and don't call uvm_wait() or do
 WAITOK ever - UVM takes care of that.


 To generate a diff of this commit:
 cvs rdiff -u -r1.81 -r1.82 src/sys/arch/vax/include/pmap.h
 cvs rdiff -u -r1.189 -r1.190 src/sys/arch/vax/vax/pmap.c

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

>Unformatted:

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