On 07/12/2011 10:25 AM, Myklebust, Trond wrote:
-----Original Message-----
From: Ben Greear [mailto:greearb@xxxxxxxxxxxxxxx]
Sent: Tuesday, July 12, 2011 1:15 PM
To: Myklebust, Trond
Cc: linux-nfs@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [RFC] sunrpc: Fix race between work-queue and
rpc_killall_tasks.
On 07/08/2011 03:14 PM, Myklebust, Trond wrote:
[<ffffffff81105907>] print_trailer+0x131/0x13a
[<ffffffff81105945>] object_err+0x35/0x3e
[<ffffffff811077b3>] verify_mem_not_deleted+0x7a/0xb7
[<ffffffffa02891e5>] rpcb_getport_done+0x23/0x126 [sunrpc]
[<ffffffffa02810df>] rpc_exit_task+0x3f/0x6d [sunrpc]
[<ffffffffa02814d8>] __rpc_execute+0x80/0x253 [sunrpc]
[<ffffffffa02816ed>] ? rpc_execute+0x42/0x42 [sunrpc]
[<ffffffffa02816fd>] rpc_async_schedule+0x10/0x12 [sunrpc]
[<ffffffff81061343>] process_one_work+0x230/0x41d
[<ffffffff8106128e>] ? process_one_work+0x17b/0x41d
[<ffffffff8106379f>] worker_thread+0x133/0x217
[<ffffffff8106366c>] ? manage_workers+0x191/0x191
[<ffffffff81066f9c>] kthread+0x7d/0x85
[<ffffffff81485ee4>] kernel_thread_helper+0x4/0x10
[<ffffffff8147f0d8>] ? retint_restore_args+0x13/0x13
[<ffffffff81066f1f>] ? __init_kthread_worker+0x56/0x56
[<ffffffff81485ee0>] ? gs_change+0x13/0x13
The calldata gets freed in the rpc_final_put_task() which shouldn't
ever be run while the task is still referenced in __rpc_execute
IOW: it should be impossible to call rpc_exit_task() after
rpc_final_put_task
I added lots of locking around the calldata, work-queue logic, and
such, and
still the problem persists w/out hitting any of the debug warnings or
poisoned
values I put in. It almost seems like tk_calldata is just assigned to
two
different tasks.
While poking through the code, I noticed that 'map' is static in
rpcb_getport_async.
That would seem to cause problems if two threads called this method at
the same time, possibly causing tk_calldata to be assigned to two
different
tasks???
Any idea why it is static?
Doh! That is clearly a typo dating all the way back to when Chuck wrote that function.
Yes, that would definitely explain your problem.
Ok, patch sent. I assume someone will propagate this to stable
as desired?
And assuming this fixes it, can I get some brownie points towards
review of the ip-addr binding patches? :)
Thanks,
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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