Hi Bruce,
I'm getting the following warning that I was able to bisect to this patch:
[ 142.149710] ------------[ cut here ]------------
[ 142.150014] WARNING: at kernel/mutex-debug.c:78 debug_mutex_unlock+0xda/0xe0()
[ 142.150258] Hardware name: Bochs
[ 142.150407] Modules linked in: md5 nfsd exportfs nfs lockd fscache auth_rpcgss nfs_acl sunrpc ipv6 ext2 snd_hda_intel snd_hda_codec snd_hwdep psmouse i2c_piix4 evdev serio_raw pcspkr virtio_balloon snd_pcm snd_timer snd soundcore snd_page_alloc floppy i2c_core button processor ext4 mbcache jbd2 crc16 pata_acpi uhci_hcd ata_piix libata usbcore scsi_mod virtio_net virtio_pci virtio_blk virtio virtio_ring
[ 142.152927] Pid: 742, comm: nfsd Not tainted 3.1.0-rc1-SLIM+ #9
[ 142.152927] Call Trace:
[ 142.152927] [<ffffffff8105fa4f>] warn_slowpath_common+0x7f/0xc0
[ 142.152927] [<ffffffff8105faaa>] warn_slowpath_null+0x1a/0x20
[ 142.152927] [<ffffffff810960ca>] debug_mutex_unlock+0xda/0xe0
[ 142.152927] [<ffffffff813e4200>] __mutex_unlock_slowpath+0x80/0x140
[ 142.152927] [<ffffffff813e42ce>] mutex_unlock+0xe/0x10
[ 142.152927] [<ffffffffa03bd3f5>] nfs4_lock_state+0x35/0x40 [nfsd]
[ 142.152927] [<ffffffffa03b0b71>] nfsd4_proc_compound+0x2a1/0x690 [nfsd]
[ 142.152927] [<ffffffffa039f9fb>] nfsd_dispatch+0xeb/0x230 [nfsd]
[ 142.152927] [<ffffffffa02b1055>] svc_process_common+0x345/0x690 [sunrpc]
[ 142.152927] [<ffffffff81058d10>] ? try_to_wake_up+0x280/0x280
[ 142.152927] [<ffffffffa02b16e2>] svc_process+0x102/0x150 [sunrpc]
[ 142.152927] [<ffffffffa039f0bd>] nfsd+0xbd/0x160 [nfsd]
[ 142.152927] [<ffffffffa039f000>] ? 0xffffffffa039efff
[ 142.152927] [<ffffffff8108230c>] kthread+0x8c/0xa0
[ 142.152927] [<ffffffff813e8694>] kernel_thread_helper+0x4/0x10
[ 142.152927] [<ffffffff81082280>] ? kthread_worker_fn+0x190/0x190
[ 142.152927] [<ffffffff813e8690>] ? gs_change+0x13/0x13
[ 142.152927] ---[ end trace 1b4070dc432138aa ]---
I can duplicate it with this python script, the warning shows up on the server after (during?) the f.close() line:
#!/usr/bin/python
import sys
import fcntl
import struct
import datetime
f = open(sys.argv[1], 'rw+')
print "Attempting to lock file:", sys.argv[1]
lockreq = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
rv = fcntl.fcntl(f, fcntl.F_SETLKW, lockreq)
raw_input("Press enter when you are ready to continue... ")
f.close()
- Bryan
On 09/14/2011 07:44 AM, J. Bruce Fields wrote:
> There are currently a couple races in the seqid replay code: a
> retransmission could come while we're still encoding the original reply,
> or a new seqid-mutating call could come as we're encoding a replay.
>
> So, extend the state lock over the encoding (both encoding of a replayed
> reply and caching of the original encoded reply).
>
> I really hate doing this, and previously added the stateowner
> reference-counting code to avoid it (which was insufficient)--but I
> don't see a less complicated alternative at the moment.
>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4proc.c | 5 +++--
> fs/nfsd/nfs4state.c | 12 ++++++++----
> 2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 50bae74..50063a8 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -408,8 +408,8 @@ out:
> if (open->op_stateowner) {
> nfs4_get_stateowner(open->op_stateowner);
> cstate->replay_owner = open->op_stateowner;
> - }
> - nfs4_unlock_state();
> + } else
> + nfs4_unlock_state();
> return status;
> }
>
> @@ -1227,6 +1227,7 @@ encode_op:
> be32_to_cpu(status));
>
> if (cstate->replay_owner) {
> + nfs4_unlock_state();
> nfs4_put_stateowner(cstate->replay_owner);
> cstate->replay_owner = NULL;
> }
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index bc1a9db..6cf729a 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -3501,7 +3501,8 @@ nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>
> nfsd4_create_clid_dir(sop->so_client);
> out:
> - nfs4_unlock_state();
> + if (!cstate->replay_owner)
> + nfs4_unlock_state();
> return status;
> }
>
> @@ -3568,7 +3569,8 @@ nfsd4_open_downgrade(struct svc_rqst *rqstp,
> memcpy(&od->od_stateid, &stp->st_stateid, sizeof(stateid_t));
> status = nfs_ok;
> out:
> - nfs4_unlock_state();
> + if (!cstate->replay_owner)
> + nfs4_unlock_state();
> return status;
> }
>
> @@ -3609,7 +3611,8 @@ nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> if (list_empty(&so->so_stateids))
> move_to_close_lru(so);
> out:
> - nfs4_unlock_state();
> + if (!cstate->replay_owner)
> + nfs4_unlock_state();
> return status;
> }
>
> @@ -4071,7 +4074,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> out:
> if (status && lock->lk_is_new && lock_sop)
> release_lockowner(lock_sop);
> - nfs4_unlock_state();
> + if (!cstate->replay_owner)
> + nfs4_unlock_state();
> return status;
> }
>
--
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