[src/trunk]: src/sys Always take the object lock before changing vmpage flags...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c12f35720988
branches:  trunk
changeset: 759136:c12f35720988
user:      hannken <hannken%NetBSD.org@localhost>
date:      Tue Nov 30 10:55:25 2010 +0000

description:
Always take the object lock before changing vmpage flags.  Fixes a deadlock
where a thread is waiting on "genput" but the page in question is neither
BUSY nor WANTED.

No objections from tech-kern@.

diffstat:

 sys/miscfs/genfs/genfs_io.c |  8 ++++++--
 sys/uvm/uvm_bio.c           |  6 +++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diffs (84 lines):

diff -r f6cea988a81d -r c12f35720988 sys/miscfs/genfs/genfs_io.c
--- a/sys/miscfs/genfs/genfs_io.c       Tue Nov 30 10:50:29 2010 +0000
+++ b/sys/miscfs/genfs/genfs_io.c       Tue Nov 30 10:55:25 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: genfs_io.c,v 1.43 2010/11/19 05:38:10 uebayasi Exp $   */
+/*     $NetBSD: genfs_io.c,v 1.44 2010/11/30 10:55:25 hannken Exp $    */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.43 2010/11/19 05:38:10 uebayasi Exp $");
+__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.44 2010/11/30 10:55:25 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -569,6 +569,7 @@
                            iobytes);
                        skipbytes += iobytes;
 
+                       mutex_enter(&uobj->vmobjlock);
                        for (i = 0; i < holepages; i++) {
                                if (memwrite) {
                                        pgs[pidx + i]->flags &= ~PG_CLEAN;
@@ -577,6 +578,7 @@
                                        pgs[pidx + i]->flags |= PG_RDONLY;
                                }
                        }
+                       mutex_exit(&uobj->vmobjlock);
                        continue;
                }
 
@@ -638,6 +640,7 @@
                UVMHIST_LOG(ubchist, "gop_alloc off 0x%x/0x%x -> %d",
                    startoffset, npages << PAGE_SHIFT, error,0);
                if (!error) {
+                       mutex_enter(&uobj->vmobjlock);
                        for (i = 0; i < npages; i++) {
                                struct vm_page *pg = pgs[i];
 
@@ -648,6 +651,7 @@
                                UVMHIST_LOG(ubchist, "mark dirty pg %p",
                                    pg,0,0,0);
                        }
+                       mutex_exit(&uobj->vmobjlock);
                }
        }
        if (!glocked) {
diff -r f6cea988a81d -r c12f35720988 sys/uvm/uvm_bio.c
--- a/sys/uvm/uvm_bio.c Tue Nov 30 10:50:29 2010 +0000
+++ b/sys/uvm/uvm_bio.c Tue Nov 30 10:55:25 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_bio.c,v 1.70 2010/06/22 18:34:50 rmind Exp $       */
+/*     $NetBSD: uvm_bio.c,v 1.71 2010/11/30 10:55:25 hannken Exp $     */
 
 /*
  * Copyright (c) 1998 Chuck Silvers.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.70 2010/06/22 18:34:50 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_bio.c,v 1.71 2010/11/30 10:55:25 hannken Exp $");
 
 #include "opt_uvmhist.h"
 #include "opt_ubc.h"
@@ -645,6 +645,7 @@
                        memset((char *)umapva + endoff, 0, zerolen);
                }
                umap->flags &= ~UMAP_PAGES_LOCKED;
+               mutex_enter(&uobj->vmobjlock);
                mutex_enter(&uvm_pageqlock);
                for (i = 0; i < npages; i++) {
                        rv = pmap_extract(pmap_kernel(),
@@ -658,7 +659,6 @@
                mutex_exit(&uvm_pageqlock);
                pmap_kremove(umapva, ubc_winsize);
                pmap_update(pmap_kernel());
-               mutex_enter(&uobj->vmobjlock);
                uvm_page_unbusy(pgs, npages);
                mutex_exit(&uobj->vmobjlock);
                unmapped = true;