This is indeed a ZFS+NFS system and I can see that istgt and nfs are stuck in
some ZIO state. Maybe it's this.
Thank's for pointing out.
Is it this ZFS+NFS deadlock?
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
@@ -3720,8 +3720,16 @@ arc_lowmem(void *arg __unused, int howto __unused)
mutex_enter(&arc_reclaim_thr_lock);
needfree = 1;
cv_signal(&arc_reclaim_thr_cv);
- while (needfree)
- msleep(&needfree, &arc_reclaim_thr_lock, 0, "zfs:lowmem", 0);
+
+ /*
+ * It is unsafe to block here in arbitrary threads, because we can come
+ * here from ARC itself and may hold ARC locks and thus risk a deadlock
+ * with ARC reclaim thread.
+ */
+ if (curproc == pageproc) {
+ while (needfree)
+ msleep(&needfree, &arc_reclaim_thr_lock, 0, "zfs:lowmem", 0);
+ }
mutex_exit(&arc_reclaim_thr_lock);
mutex_exit(&arc_lowmem_lock);
}
I'll try to crash our testsystem. I'll assume that stressing NFS backed with
ZFS a lot might trigger this bug?
-dennis
Am 16.05.2013 um 00:03 schrieb Steven Hartland:
> ----- Original Message ----- From: "dennis berger" <[email protected]>
>> FreeBSD 9.1-RELEASE FreeBSD 9.1-RELEASE #0 r243825: Tue Dec 4 09:23:10 UTC
>> 2012
>>
>>> 3. Regarding this:
>>>>> A clean shutdown isn't possible though. It hangs after vnode
>>>>> cleaning, normally you would see detaching of usb devices here, or
>>>>> other devices maybe?
>>> Please don't conflate this with your above issue. This is almost
>>> certainly unrelated. Please start a new thread about that if desired.
>>
>> Maybe this is a misunderstanding normally this system will shutdown cleanly,
>> of course.
>> This hang only appears after the network problem above.
>
> If this is a ZFS system, its a known issue which is fixed in current,
> stable-9, stable-8 and the upcoming 8.4 release.
>
> If not and you have USB devices see if the following sysctl helps:
> hw.usb.no_shutdown_wait=1
>
> Regards
> Steve
>
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