Date: Sat, 17 May 2003 22:35:57 -0700 From: David Schultz <das@FreeBSD.ORG> To: Giorgos Keramidas <keramida@ceid.upatras.gr> Cc: current@FreeBSD.ORG Subject: Re: Panic with swap-backed md devices Message-ID: <20030518053557.GA223@HAL9000.homeunix.com> In-Reply-To: <20030514232428.GA731@gothmog.gr> References: <20030514232428.GA731@gothmog.gr>
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On Thu, May 15, 2003, Giorgos Keramidas wrote:
> Trying to create and destroy a swap-backed md device results in panics
> with today's CURRENT. I was trying to make a new -t swap md disk to
> test the problem described in a PR. Using the following small shell
> script I noticed that it always causes a panic when mdconfig -d is run:
>
> mdconfig -a -t swap -s 100m -u 10
> disklabel -r -w md10 auto
> newfs -O 1 -b 8192 -s 1024 md10
> mount /dev/md10 /mnt
> mount
> umount /mnt
> mount
> mdconfig -d -u 10
The following patch should fix the panic, but there's a small
vm_object leak that's still unfixed. I'll look into that.
Index: sys/dev/md/md.c
===================================================================
RCS file: /cvs/src/sys/dev/md/md.c,v
retrieving revision 1.98
diff -u -r1.98 md.c
--- sys/dev/md/md.c 2 May 2003 06:18:58 -0000 1.98
+++ sys/dev/md/md.c 18 May 2003 04:04:23 -0000
@@ -932,7 +932,9 @@
if (sc->cred != NULL)
crfree(sc->cred);
if (sc->object != NULL) {
+ VM_OBJECT_LOCK(sc->object);
vm_pager_deallocate(sc->object);
+ VM_OBJECT_UNLOCK(sc->object);
}
if (sc->indir)
destroy_indir(sc, sc->indir);
@@ -990,7 +992,9 @@
sc->flags = mdio->md_options & MD_FORCE;
if (mdio->md_options & MD_RESERVE) {
if (swap_pager_reserve(sc->object, 0, sc->nsect) < 0) {
+ VM_OBJECT_LOCK(sc->object);
vm_pager_deallocate(sc->object);
+ VM_OBJECT_UNLOCK(sc->object);
sc->object = NULL;
mddestroy(sc, td);
return (EDOM);
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