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* 2.6.19.3 client locking bug upon server reboot
@ 2007-02-26 14:15 Frank van Maarseveen
  2007-03-02 20:15 ` 2.6.x client locking bug upon server reboot (2) Frank van Maarseveen
  0 siblings, 1 reply; 2+ messages in thread
From: Frank van Maarseveen @ 2007-02-26 14:15 UTC (permalink / raw)
  To: Linux NFS mailing list

2.6.19.3, NFS V3, portmap V2, stat V1, nlm, all UDP

one server, three clients:

client1 has the lock
client2 wants the lock (fcntl blocks)
client3 will try to lock right after server has rebooted and started everything

On the server, /etc/rc2.d/S06xxxx is created to start a

	tcpdump -i eth0 -p -w /tmp/log -s 1500 >/dev/null 2>&1 &

upon the next reboot right after eth0 becomes up.

I type alt-sysrq-b on the server after a few "sync" commands. After >5
minutes client1 releases the lock and client3 obtains the lock. A few
seconds later client3 releases the lock.

	nothing happens

client2 did not try to obtain a lock anyhow since server reboot. Instead,
it hangs in rpc_wait_bit_interruptible(), only kill -9 could kill it.

The log written by tcpdump has been analyzed afterwards using wireshark
(t=<time since start>):

t=10	server->(all 3 clients): portmap getport STAT, all clients reply
	server->(all 3 clients): STAT notify, all clients reply
	client1->server: portmap getport NLM, server replies
	client1->server: NLM lock, server replies.

t=15	client3->server: portmap getport NLM, server replies
	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=20	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=25	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=30	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=35	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=40	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=45	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=50	client3->server: NLM lock, server says: NLM_DENIED_GRACE_PERIOD
t=55	client3->server: NLM lock, server says: NLM_BLOCKED
t=85	client3->server: portmap getport NLM, server replies

t=115	client3->server: NLM lock, server says: NLM_BLOCKED

[...]

t=383	client1->server: portmap getport NLM, server replies
	client1->server: NLM unlock, server replies
	server->client3: portmap getport NLM, client replies
	server->client3: NLM NULL, client replies
	server->client3: NLM GRANTED_MSG
	client3->server: portmap getport NLM, server replies
	client3->server: NLM NULL, server replies.
	client3->server: NLM GRANTED_RES, server replies.
	client3->server: reply for NLM GRANTED_MSG

t=390	client3->server: portmap getport NLM, server replies
	client3->server: NLM unlock, server replies.

Notice the absence of any client2 traffic for t>10. There is no
interesting traffic around t=10 whatsoever for client2 other than what
has been mentioned. This bug is probably reproducable without the third
client but anyway, the above is what happened during the test.

-- 
Frank

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^ permalink raw reply	[flat|nested] 2+ messages in thread
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2007-02-26 14:15 2.6.19.3 client locking bug upon server reboot Frank van Maarseveen
2007-03-02 20:15 ` 2.6.x client locking bug upon server reboot (2) Frank van Maarseveen

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