From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Staubach Subject: Re: [pnfs] nfs41: sunrpc: handle clnt==NULL in call_status Date: Tue, 04 Nov 2008 11:09:00 -0500 Message-ID: <4910739C.2010405@redhat.com> References: <49106FCB.1090303@panasas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: Trond Myklebust , NFS list , pNFS Mailing List To: Benny Halevy Return-path: Received: from mx2.redhat.com ([66.187.237.31]:52224 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753524AbYKDQJN (ORCPT ); Tue, 4 Nov 2008 11:09:13 -0500 In-Reply-To: <49106FCB.1090303@panasas.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Benny Halevy wrote: > On the following error path task->tk_client == NULL causing NULL deref: > > Nov 4 14:14:32 tl1 kernel: Callback slot table overflowed > Nov 4 14:14:32 tl1 kernel: BUG: unable to handle kernel NULL pointer dereference at 0000000000000078 > Nov 4 14:14:32 tl1 kernel: IP: [] call_status+0xe1/0x145 [sunrpc] > Nov 4 14:14:32 tl1 kernel: PGD 2f973067 PUD 2f974067 PMD 0 > Nov 4 14:14:32 tl1 kernel: Oops: 0000 [1] SMP > Nov 4 14:14:32 tl1 kernel: CPU 0 > Nov 4 14:14:32 tl1 kernel: Modules linked in: panfs(P) panlayoutdriver nfslayoutdriver nfsd auth_rpcgss exportfs nfs lockd nfs_acl fuse sunrpc ipv6 cpufreq_ondemand powernow_k8 freq_table dm_mirror dm_log dm_multipath dm_mod snd_hda_intel snd_seq_dummy sr_mod snd_seq_oss cdrom snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd_page_alloc snd_hwdep snd pcspkr serio_raw k8temp hwmon forcedeth soundcore pata_amd sg jedec_probe cfi_probe gen_probe mtd i2c_nforce2 chipreg i2c_core button map_funcs sata_nv ata_generic pata_acpi libata sd_mod scsi_mod ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd [last unloaded: scsi_wait_scan] > Nov 4 14:14:32 tl1 kernel: Pid: 3405, comm: nfsv4.1-svc Tainted: P 2.6.27-pnfs #1 > Nov 4 14:14:32 tl1 kernel: RIP: 0010:[] [] call_status+0xe1/0x145 [sunrpc] > Nov 4 14:14:32 tl1 kernel: RSP: 0018:ffff88002a70bd60 EFLAGS: 00010246 > Nov 4 14:14:32 tl1 kernel: RAX: 0000000000000000 RBX: 00000000ffffff95 RCX: 0000000000000000 > Nov 4 14:14:32 tl1 kernel: RDX: ffff88002a70bd10 RSI: ffff88002fc52dc0 RDI: ffff88002fc52dc0 > Nov 4 14:14:32 tl1 kernel: RBP: ffff88002a70bd80 R08: ffff88002f9dae40 R09: ffffffff81489e60 > Nov 4 14:14:32 tl1 kernel: R10: ffff880038497800 R11: ffff88002a70bd30 R12: ffff88002fc52dc0 > Nov 4 14:14:32 tl1 kernel: R13: 0000000000000000 R14: ffff88002f57fa00 R15: ffff88002fc52e50 > Nov 4 14:14:32 tl1 kernel: FS: 00007fe78ffac6f0(0000) GS:ffffffff8148da80(0000) knlGS:0000000000000000 > Nov 4 14:14:32 tl1 kernel: CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b > Nov 4 14:14:32 tl1 kernel: CR2: 0000000000000078 CR3: 000000002f971000 CR4: 00000000000006e0 > Nov 4 14:14:32 tl1 kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > Nov 4 14:14:32 tl1 kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Nov 4 14:14:32 tl1 kernel: Process nfsv4.1-svc (pid: 3405, threadinfo ffff88002a70a000, task ffff88003694d900) > Nov 4 14:14:32 tl1 kernel: Stack: 0000000000000000 ffff88002f57fa00 ffff88002fc52dc0 ffff880030450ce8 > Nov 4 14:14:32 tl1 kernel: ffff88002a70bdc0 ffffffffa02bb9db ffff88002a70bdf0 ffff88002fc52dc0 > Nov 4 14:14:32 tl1 kernel: ffff88002f57fa00 ffff88002f57fa00 ffff880030450ce8 ffff88002a734000 > Nov 4 14:14:32 tl1 kernel: Call Trace: > Nov 4 14:14:32 tl1 kernel: [] __rpc_execute+0x7e/0x21f [sunrpc] > Nov 4 14:14:32 tl1 kernel: [] rpc_execute+0x28/0x2c [sunrpc] > Nov 4 14:14:32 tl1 kernel: [] rpc_run_bc_task+0x88/0xae [sunrpc] > Nov 4 14:14:32 tl1 kernel: [] bc_send+0x35/0x5a [sunrpc] > Nov 4 14:14:32 tl1 kernel: [] bc_svc_process+0xf6/0x101 [sunrpc] > Nov 4 14:14:32 tl1 kernel: [] ? prepare_to_wait+0x5c/0x65 > Nov 4 14:14:32 tl1 kernel: [] nfs41_callback_svc+0xda/0x131 [nfs] > Nov 4 14:14:32 tl1 kernel: [] ? autoremove_wake_function+0x0/0x38 > Nov 4 14:14:32 tl1 kernel: [] ? nfs41_callback_svc+0x0/0x131 [nfs] > Nov 4 14:14:32 tl1 kernel: [] kthread+0x49/0x76 > Nov 4 14:14:32 tl1 kernel: [] child_rip+0xa/0x11 > Nov 4 14:14:32 tl1 kernel: [] ? pick_next_task_fair+0x93/0xa3 > Nov 4 14:14:32 tl1 kernel: [] ? kthread+0x0/0x76 > Nov 4 14:14:32 tl1 kernel: [] ? child_rip+0x0/0x11 > Nov 4 14:14:32 tl1 kernel: > Nov 4 14:14:32 tl1 kernel: > Nov 4 14:14:32 tl1 kernel: Code: e8 7c 70 00 00 49 8b 44 24 20 49 c7 44 24 68 dc 48 2b a0 f6 40 78 02 74 6d 41 8b b6 34 01 00 00 48 8b 78 30 e8 b9 2a 00 00 eb 5b <41> f6 45 78 04 74 13 49 8b 55 30 48 8d 82 80 04 00 00 f0 80 a2 > Nov 4 14:14:32 tl1 kernel: RIP [] call_status+0xe1/0x145 [sunrpc] > Nov 4 14:14:32 tl1 kernel: RSP > Nov 4 14:14:32 tl1 kernel: CR2: 0000000000000078 > Nov 4 14:14:32 tl1 kernel: ---[ end trace 1584c489f2573aaf ]--- > > Signed-off-by: Benny Halevy > --- > > Trond, I'm not sure if this can happen without nfs41. > However, please consider this patch for upstream since > it is safe to do in any case. > > Benny > > net/sunrpc/clnt.c | 8 +++++--- > 1 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c > index 78fc483..b555d9f 100644 > --- a/net/sunrpc/clnt.c > +++ b/net/sunrpc/clnt.c > @@ -1206,7 +1206,8 @@ call_status(struct rpc_task *task) > break; > case -ECONNREFUSED: > case -ENOTCONN: > - rpc_force_rebind(clnt); > + if (clnt) > + rpc_force_rebind(clnt); > task->tk_action = call_bind; > break; > case -EAGAIN: > @@ -1217,9 +1218,10 @@ call_status(struct rpc_task *task) > rpc_exit(task, status); > break; > default: > - if (clnt->cl_chatty) > + if (!clnt || clnt->cl_chatty) > printk("%s: RPC call returned error %d\n", > - clnt->cl_protname, -status); > + clnt ? clnt->cl_protname : "", > + -status); > Is this message useful if clnt == NULL? How would one go about debugging if the message appears with "" in it? Thanx... ps > rpc_exit(task, status); > } > } > _______________________________________________ > pNFS mailing list > pNFS@linux-nfs.org > http://linux-nfs.org/cgi-bin/mailman/listinfo/pnfs >