Re: [SUNPRC] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070

Re: [SUNPRC] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070

[Myklebust, Trond]

On Fri, 2013-01-11 at 10:46 +0800, Fengguang Wu wrote:
> tree:   git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next
> commit: 51b63a538c54cb9c3b83c4d62572cf18da165cba [1/1] SUNRPC: Ensure we release the socket write lock if the rpc_task exits early
> 
> [  106.308511] md: autorun ...
> [  106.309477] md: ... autorun DONE.
> [  107.923634] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070
> [  107.926207] IP: [<ffffffff82a7c8ac>] xprt_release+0x24/0x1cb
> [  107.927223] PGD 0 
> [  107.927223] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
> [  107.927223] Modules linked in:
> [  107.927223] CPU 1 
> [  107.927223] Pid: 1, comm: swapper/0 Not tainted 3.8.0-rc2-00187-gf958f23 #1651 Bochs Bochs
> [  107.927223] RIP: 0010:[<ffffffff82a7c8ac>]  [<ffffffff82a7c8ac>] xprt_release+0x24/0x1cb
> [  107.927223] RSP: 0000:ffff88001d831908  EFLAGS: 00010246
> [  107.927223] RAX: 0000000000000000 RBX: ffff88001bff1080 RCX: ffff88001f400000
> [  107.927223] RDX: 0000000000000002 RSI: 000000000000051c RDI: ffff88001bff1080
> [  107.927223] RBP: ffff88001d831938 R08: 000000000000051c R09: 0000000000000004
> [  107.927223] R10: 000000000000332e R11: ffff88001bff1080 R12: 0000000000000000
> [  107.927223] R13: ffff88001bff1080 R14: ffff880010008380 R15: 000000000000000c
> [  107.927223] FS:  0000000000000000(0000) GS:ffff88001f400000(0000) knlGS:0000000000000000
> [  107.927223] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [  107.927223] CR2: 0000000000000070 CR3: 0000000003c15000 CR4: 00000000000006e0
> [  107.927223] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  107.927223] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [  107.927223] Process swapper/0 (pid: 1, threadinfo ffff88001d830000, task ffff88001e27c040)
> [  107.927223] Stack:
> [  107.927223]  000000000000332e ffff88001bff1080 ffff880010722e00 0000000000008000
> [  107.927223]  ffff880010008380 000000000000000c ffff88001d831958 ffffffff82a80445
> [  107.927223]  000000000000332e ffff88001bff1080 ffff88001d831978 ffffffff82a81cfa
> [  107.927223] Call Trace:
> [  107.927223]  [<ffffffff82a80445>] rpc_release_resources_task+0x14/0x37
> [  107.927223]  [<ffffffff82a81cfa>] rpc_put_task+0x1f/0x2d
> [  107.927223]  [<ffffffff82a7b002>] rpc_call_sync+0x69/0x9e
> [  107.927223]  [<ffffffff82a79942>] ? net_generic.isra.10+0x2e/0x3d
> [  107.927223]  [<ffffffff82a7b07e>] rpc_ping+0x47/0x5d
> [  107.927223]  [<ffffffff82a7a42d>] ? rpc_new_client+0x2c8/0x331
> [  107.927223]  [<ffffffff82a7b231>] rpc_create+0x11b/0x1ad
> [  107.927223]  [<ffffffff810e5bc4>] ? trace_hardirqs_off+0xd/0xf
> [  107.927223]  [<ffffffff810e8090>] ? mark_lock+0x2d/0x212
> [  107.927223]  [<ffffffff812f24ce>] nfs_mount+0xdf/0x140
> [  107.927223]  [<ffffffff812eaa1c>] nfs_request_mount+0x114/0x170
> [  107.927223]  [<ffffffff810e93e4>] ? lock_release+0x17d/0x1cd
> [  107.927223]  [<ffffffff812eaaa7>] nfs_try_mount+0x2f/0x6d
> [  107.927223]  [<ffffffff812ebbcf>] nfs_fs_mount+0x6cf/0x7ad
> [  107.927223]  [<ffffffff812ec0a5>] ? nfs_clone_super+0x6b/0x6b
> [  107.927223]  [<ffffffff812e98f3>] ? nfs_clone_sb_security+0x51/0x51
> [  107.927223]  [<ffffffff81194055>] mount_fs+0x69/0x158
> [  107.927223]  [<ffffffff8116190a>] ? __alloc_percpu+0x10/0x12
> [  107.927223]  [<ffffffff811a9158>] vfs_kern_mount+0x62/0xd9
> [  107.927223]  [<ffffffff811ab23d>] do_mount+0x763/0x875
> [  107.927223]  [<ffffffff811ab3d4>] sys_mount+0x85/0xbe
> [  107.927223]  [<ffffffff841690d4>] mount_root+0x61/0x14f
> [  107.927223]  [<ffffffff8416932f>] prepare_namespace+0x16d/0x1a6
> [  107.927223]  [<ffffffff82bdcb9b>] kernel_init+0x1c5/0x29b
> [  107.927223]  [<ffffffff84168590>] ? do_early_param+0x8c/0x8c
> [  107.927223]  [<ffffffff82bdc9d6>] ? rest_init+0xda/0xda
> [  107.927223]  [<ffffffff82c260ac>] ret_from_fork+0x7c/0xb0
> [  107.927223]  [<ffffffff82bdc9d6>] ? rest_init+0xda/0xda
> [  107.927223] Code: 89 e5 ff 50 18 5d c3 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 55 49 89 fd 41 54 53 41 52 4c 8b 67 20 4d 85 e4 75 22 48 8b 47 18 <48> 8b 78 70 48 8b b7 70 07 00 00 4c 39 ee 0f 85 86 01 00 00 e8 
> [  107.927223] RIP  [<ffffffff82a7c8ac>] xprt_release+0x24/0x1cb
> [  107.927223]  RSP <ffff88001d831908>
> [  107.927223] CR2: 0000000000000070
> 
> Thanks,
> Fengguang

Hi Fengguang,

Thanks for testing! The above Oops should be fixed in commit
87ed50036b866db2ec2ba16b2a7aec4a2b0b7c39, which is in the current
linux-next branch on git.linux-nfs.org. It was due to a missing test for
task->tk_client != NULL.

I should also have fixed the RCU dereference warning that the build
robot found on Tuesday.

Cheers
  Trond

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@netapp.com
www.netapp.com

Re: [SUNPRC] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070

[Fengguang Wu]

On Fri, Jan 11, 2013 at 04:24:45AM +0000, Trond Myklebust wrote:
> On Fri, 2013-01-11 at 10:46 +0800, Fengguang Wu wrote:
> > tree:   git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next
> > commit: 51b63a538c54cb9c3b83c4d62572cf18da165cba [1/1] SUNRPC: Ensure we release the socket write lock if the rpc_task exits early
> > 
> > [  106.308511] md: autorun ...
> > [  106.309477] md: ... autorun DONE.
> > [  107.923634] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070
> > [  107.926207] IP: [<ffffffff82a7c8ac>] xprt_release+0x24/0x1cb

> Hi Fengguang,
> 
> Thanks for testing! The above Oops should be fixed in commit
> 87ed50036b866db2ec2ba16b2a7aec4a2b0b7c39, which is in the current
> linux-next branch on git.linux-nfs.org. It was due to a missing test for
> task->tk_client != NULL.

Yes, sorry that bug was actually caught several days before, however
I was too busy to look into it..

> I should also have fixed the RCU dereference warning that the build
> robot found on Tuesday.

Trond, thank you for the fixes!

Thanks,
Fengguang