I'm having a little trouble debugging this sunrpc module refcnt leak in
nfsd. Perhaps a fresh pair of eyes can help.
nfsd leaks 3 references to the sunrpc module here:
# echo -n "asdf 1234" >/proc/fs/nfsd/portlist
bash: echo: write error: Protocol not supported
Now stop nfsd and try unloading the kernel modules:
# systemctl stop nfs-server
# systemctl stop nfs
# systemctl stop proc-fs-nfsd.mount
# systemctl stop var-lib-nfs-rpc_pipefs.mount
# rmmod nfsd
# rmmod nfs_acl
# rmmod lockd
# rmmod auth_rpcgss
# rmmod sunrpc
rmmod: ERROR: Module sunrpc is in use
# lsmod | grep rpc
sunrpc 315392 3
I have reproduced this from source with a tree based on Linux 4.2-rc3
and also with Linux 4.1.6-200.fc22.x86_64.
The following unmatched module_get() calls are recorded by perf record
-e module:module_get -e module:module_put. Perhaps the backtrace is a
little mangled because I don't see xdr_reserve_space() calls in
svc_create_pooled() (even indirectly):
nfsd 4291 [002] 87.914752: module:module_get: sunrpc call_site=0xffffffffa031c86as refcnt=7
318d93 try_module_get (vmlinux)
98da xs_tcp_setup_socket ([sunrpc])
5ca5 xprt_create_transport ([sunrpc])
34ad rpc_create ([sunrpc])
1892a rpcb_getport_async ([sunrpc])
196ea xdr_reserve_space ([sunrpc])
128dc svc_create_pooled ([sunrpc])
686 nfsd_create_serv ([nfsd])
1be9 write_ports ([nfsd])
182c nfsctl_transaction_write ([nfsd])
410d87 __vfs_write (vmlinux)
411706 vfs_write (vmlinux)
4123f5 sys_write (vmlinux)
95ed95 tracesys_phase2 (vmlinux)
f2ff0 __GI___libc_write (/usr/lib64/libc-2.21.so)
nfsd 4291 [002] 87.914775: module:module_get: sunrpc call_site=0xffffffffa03228a5s refcnt=8
318d93 try_module_get (vmlinux)
f915 rpcauth_cache_do_shrink ([sunrpc])
2bbd rpc_new_client ([sunrpc])
337a rpc_create_xprt ([sunrpc])
34d6 rpc_create ([sunrpc])
1892a rpcb_getport_async ([sunrpc])
196ea xdr_reserve_space ([sunrpc])
128dc svc_create_pooled ([sunrpc])
686 nfsd_create_serv ([nfsd])
1be9 write_ports ([nfsd])
182c nfsctl_transaction_write ([nfsd])
410d87 __vfs_write (vmlinux)
411706 vfs_write (vmlinux)
4123f5 sys_write (vmlinux)
95ed95 tracesys_phase2 (vmlinux)
f2ff0 __GI___libc_write (/usr/lib64/libc-2.21.so)
nfsd 4291 [002] 87.914936: module:module_get: sunrpc call_site=0xffffffffa03228a5s refcnt=9
318d93 try_module_get (vmlinux)
f915 rpcauth_cache_do_shrink ([sunrpc])
2bbd rpc_new_client ([sunrpc])
2ead __rpc_clone_client ([sunrpc])
35e7 rpc_bind_new_program ([sunrpc])
18949 rpcb_getport_async ([sunrpc])
196ea xdr_reserve_space ([sunrpc])
128dc svc_create_pooled ([sunrpc])
686 nfsd_create_serv ([nfsd])
1be9 write_ports ([nfsd])
182c nfsctl_transaction_write ([nfsd])
410d87 __vfs_write (vmlinux)
411706 vfs_write (vmlinux)
4123f5 sys_write (vmlinux)
95ed95 tracesys_phase2 (vmlinux)
f2ff0 __GI___libc_write (/usr/lib64/libc-2.21.so)
In this trace I modified nfs-utils nfsd to write to portlist but you get
the same result with echo from a shell (as shown above).
Any ideas?
Stefan
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