While running nfs alpha mixed tests with 4 glusterfs servers and 4 gnfs servers and 8 clients . Following glusterfs core found.
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(gdb) bt full
#0  0x00002aaaaacee419 in hash_dentry (parent=0x6ecf68, name=0x0, mod=14057) at inode.c:63
	hash = 0
	ret = 0
#1  0x00002aaaaacef59e in __dentry_grep (table=0x63d428, parent=0x6ecf68, name=0x0) at inode.c:565
	hash = 0
	dentry = (dentry_t *) 0x0
	tmp = (dentry_t *) 0x0
#2  0x00002aaaaacef666 in inode_grep (table=0x63d428, parent=0x6ecf68, name=0x0) at inode.c:586
	inode = (inode_t *) 0x0
	dentry = (dentry_t *) 0x0
#3  0x00002aaaacb95069 in resolve_entry_simple (frame=0x2aaab4553500) at server-resolve.c:364
	state = (server_state_t *) 0x2aaab4686f08
	this = (xlator_t *) 0x6346d8
	resolve = (server_resolve_t *) 0x2aaab4686f78
	parent = (inode_t *) 0x6ecf68
	inode = (inode_t *) 0x0
	ret = 0
	__FUNCTION__ = "resolve_entry_simple"
#4  0x00002aaaacb951ed in server_resolve_entry (frame=0x2aaab4553500) at server-resolve.c:419
	state = (server_state_t *) 0x2aaab4686f08
	ret = 0
	loc = (loc_t *) 0x2aaab4686f28
#5  0x00002aaaacb95524 in server_resolve (frame=0x2aaab4553500) at server-resolve.c:548
	state = (server_state_t *) 0x2aaab4686f08
	resolve = (server_resolve_t *) 0x2aaab4686f78
#6  0x00002aaaacb95655 in server_resolve_all (frame=0x2aaab4553500) at server-resolve.c:605
	state = (server_state_t *) 0x2aaab4686f08
	this = (xlator_t *) 0x6346d8
	__FUNCTION__ = "server_resolve_all"
#7  0x00002aaaacb9574d in resolve_and_resume (frame=0x2aaab4553500, fn=0x2aaaacba5ff9 <server_lookup_resume>) at server-resolve.c:635
	state = (server_state_t *) 0x2aaab4686f08
#8  0x00002aaaacbab37b in server_lookup (req=0x2aaaabb85948) at server3_1-fops.c:4813
	frame = (call_frame_t *) 0x2aaab4553500
	conn = (server_connection_t *) 0x64acb8
	state = (server_state_t *) 0x2aaab4686f08
	xattr_req = (dict_t *) 0x0
	buf = 0x0
	args = {gfs_id = 27, ino = 0, par = 37684044, gen = 5502220811211473897, flags = 0, path = 0x7fff663d4e20 "", bname = 0x7fff663d0e20 "", dict = {
    dict_len = 0, dict_val = 0x7fff663cce20 ""}}
	ret = 0
	path = '\0' <repeats 16383 times>
	bname = '\0' <repeats 16383 times>
	dict_val = '\0' <repeats 16383 times>
	__FUNCTION__ = "server_lookup"
#9  0x00002aaaaaf2bde5 in rpcsvc_handle_rpc_call (conn=0x6568e8, msg=0x2aaab4436bb8) at rpcsvc.c:1195
	actor = (rpcsvc_actor_t *) 0x2aaaacdb4bc0
	req = (rpcsvc_request_t *) 0x2aaaabb85948
	ret = -1
	__FUNCTION__ = "rpcsvc_handle_rpc_call"
#10 0x00002aaaaaf2bfc6 in rpcsvc_notify (trans=0x65fae8, mydata=0x6568e8, event=RPC_TRANSPORT_MSG_RECEIVED, data=0x2aaab4436bb8) at rpcsvc.c:1241
	conn = (rpcsvc_conn_t *) 0x6568e8
	ret = -1
	msg = (rpc_transport_pollin_t *) 0x2aaab4436bb8
	new_trans = (rpc_transport_t *) 0x0
	__FUNCTION__ = "rpcsvc_notify"
#11 0x00002aaaaaf3109b in rpc_transport_notify (this=0x65fae8, event=RPC_TRANSPORT_MSG_RECEIVED, data=0x2aaab4436bb8) at rpc-transport.c:1239
	ret = -1
#12 0x00002aaaacfbe7c3 in socket_event_poll_in (this=0x65fae8) at socket.c:1406
	ret = 0
	pollin = (rpc_transport_pollin_t *) 0x2aaab4436bb8
#13 0x00002aaaacfbeab7 in socket_event_handler (fd=8, idx=3, data=0x65fae8, poll_in=1, poll_out=0, poll_err=0) at socket.c:1512
	this = (rpc_transport_t *) 0x65fae8
	priv = (socket_private_t *) 0x65acc8
	ret = 0
	__FUNCTION__ = "socket_event_handler"
#14 0x00002aaaaad038e4 in event_dispatch_epoll_handler (event_pool=0x62b218, events=0x63a988, i=0) at event.c:812
	event_data = (struct event_data *) 0x63a98c
	handler = (event_handler_t) 0x2aaaacfbea00 <socket_event_handler>
	data = (void *) 0x65fae8
	idx = 3
	ret = -1
	__FUNCTION__ = "event_dispatch_epoll_handler"
#15 0x00002aaaaad03ac5 in event_dispatch_epoll (event_pool=0x62b218) at event.c:876
	events = (struct epoll_event *) 0x63a988
	size = 1
	i = 0
	ret = 1
	__FUNCTION__ = "event_dispatch_epoll"
#16 0x00002aaaaad03ddb in event_dispatch (event_pool=0x62b218) at event.c:984
	ret = -1
	__FUNCTION__ = "event_dispatch"
#17 0x0000000000405062 in main (argc=7, argv=0x7fff663d9368) at glusterfsd.c:1273
	ctx = (glusterfs_ctx_t *) 0x629010
	ret = 0
(gdb) 


==========
log file-
=======
[2010-08-06 18:25:28.511788] T [server3_1-fops.c:254:server_inodelk_cbk] server-tcp: 10758552: INODELK /nfsalpha2/ip-10-245-210-193/test7/linux-2.6.35/arch/mn10300/include/asm/page_offset.h (41338621) ==> -1 (Success)
[2010-08-06 18:25:28.511808] T [rpcsvc.c:1513:rpcsvc_submit_generic] rpc-service: Tx message: 16
[2010-08-06 18:25:28.511825] T [rpcsvc.c:1319:rpcsvc_record_build_header] rpc-service: Reply fraglen 40, payload: 16, rpc hdr: 24
[2010-08-06 18:25:28.520723] T [rpcsvc-auth.c:276:rpcsvc_auth_request_init] rpc-service: Auth handler: AUTH_GLUSTERFS
[2010-08-06 18:25:28.599687] T [rpcsvc.c:1119:rpcsvc_request_create] rpc-service: RPC XID: b0dbdc, Ver: 2, Program: 1298437, ProgVers: 310, Proc: 27
[2010-08-06 18:25:28.594181] T [rpcsvc.c:1513:rpcsvc_submit_generic] rpc-service: Tx message: 332
[2010-08-06 18:25:28.593957] T [rpcsvc.c:1513:rpcsvc_submit_generic] rpc-service: Tx message: 200
[2010-08-06 18:25:28.599733] T [auth-glusterfs.c:176:auth_glusterfs_authenticate] rpc-service: Auth Info: pid: 0, uid: 0, gid: 0, owner: 0
[2010-08-06 18:25:28.599786] T [rpcsvc.c:955:rpcsvc_program_actor] rpc-service: Actor found: GlusterFS-3.1.0 - LOOKUP
pending frames:

patchset: v3.1.0qa3
signal received: 11
time of crash: 2010-08-06 18:25:28
configuration details:
argp 1
backtrace 1
dlfcn 1
fdatasync 1
libpthread 1
llistxattr 1
setfsid 1
spinlock 1
epoll.h 1
xattr.h 1
st_atim.tv_nsec 1
package-string: glusterfs 3.1.0qa3
[2010-08-06 18:25:28.599752] T [rpcsvc.c:1319:rpcsvc_record_build_header] rpc-service: Reply fraglen 224, payload: 200, rpc hdr: 24
[2010-08-06 18:25:28.599727] T [rpcsvc.c:1319:rpcsvc_record_build_header] rpc-service: Reply fraglen 356, payload: 332, rpc hdr: 24
/lib64/libc.so.6[0x2aaaab7aaf30]
/opt/glusterfs/3.1.0qa3//lib/libglusterfs.so.0[0x2aaaaacee419]
/opt/glusterfs/3.1.0qa3//lib/libglusterfs.so.0(__dentry_grep+0x42)[0x2aaaaacef59e]
/opt/glusterfs/3.1.0qa3//lib/libglusterfs.so.0(inode_grep+0x3e)[0x2aaaaacef666]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/xlator/protocol/server.so(resolve_entry_simple+0x1c9)[0x2aaaacb95069]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/xlator/protocol/server.so(server_resolve_entry+0x4a)[0x2aaaacb951ed]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/xlator/protocol/server.so(server_resolve+0x69)[0x2aaaacb95524]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/xlator/protocol/server.so(server_resolve_all+0x76)[0x2aaaacb95655]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/xlator/protocol/server.so(resolve_and_resume+0x3c)[0x2aaaacb9574d]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/xlator/protocol/server.so(server_lookup+0x38b)[0x2aaaacbab37b]
/opt/glusterfs/3.1.0qa3//lib/libgfrpc.so.0(rpcsvc_handle_rpc_call+0x19b)[0x2aaaaaf2bde5]
/opt/glusterfs/3.1.0qa3//lib/libgfrpc.so.0(rpcsvc_notify+0x167)[0x2aaaaaf2bfc6]
/opt/glusterfs/3.1.0qa3//lib/libgfrpc.so.0(rpc_transport_notify+0xd8)[0x2aaaaaf3109b]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/rpc-transport/socket.so(socket_event_poll_in+0x4b)[0x2aaaacfbe7c3]
/opt/glusterfs/3.1.0qa3//lib/glusterfs/3.1.0qa3/rpc-transport/socket.so(socket_event_handler+0xb7)[0x2aaaacfbeab7]
/opt/glusterfs/3.1.0qa3//lib/libglusterfs.so.0[0x2aaaaad038e4]
/opt/glusterfs/3.1.0qa3//lib/libglusterfs.so.0[0x2aaaaad03ac5]
/opt/glusterfs/3.1.0qa3//lib/libglusterfs.so.0(event_dispatch+0x73)[0x2aaaaad03ddb]
/opt/glusterfs/3.1.0qa3/sbin/glusterfsd(main+0xec)[0x405062]
/lib64/libc.so.6(__libc_start_main+0xf4)[0x2aaaab798074]
/opt/glusterfs/3.1.0qa3/sbin/glusterfsd[0x4027a9]
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