Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0

From: Michal Schmidt
Date: Mon Oct 25 2004 - 16:55:35 EST

Ingo Molnar wrote:
i have released the -V0 Real-Time Preemption patch, which can be
downloaded from:

http://redhat.com/~mingo/realtime-preempt/

I'm testing -V0.2. I'm getting reproducible deadlocks very soon after I start anything talking to network (firefox, links, licq).
Example with links:

BUG: semaphore recursion deadlock detected!
.. current task links/4724 is already holding c0430840.
[<c01c7546>] __rwsem_deadlock+0x176/0x190 (12)
[<c02cb966>] down_write+0x116/0x250 (20)
[<c01c743c>] __rwsem_deadlock+0x6c/0x190 (28)
[<c02cb839>] down_read+0x39/0x50 (20)
[<c02cb8b2>] down_write+0x62/0x250 (4)
[<c02cb966>] down_write+0x116/0x250 (24)
[<c02cb839>] down_read+0x39/0x50 (48)
[<c0114310>] mcount+0x14/0x18 (12)
[<c0271c91>] dev_queue_xmit_nit+0x41/0x130 (28)
[<c01c7bf6>] up_write+0x26/0x60 (12)
[<c0281443>] qdisc_restart+0x223/0x250 (24)
[<c027221d>] dev_queue_xmit+0x1ad/0x260 (12)
[<c0114310>] mcount+0x14/0x18 (8)
[<c027222f>] dev_queue_xmit+0x1bf/0x260 (36)
[<c027856e>] neigh_resolve_output+0xfe/0x240 (32)
[<c029327e>] ip_finish_output2+0xbe/0x240 (56)
[<c027dc45>] nf_hook_slow+0xd5/0x130 (36)
[<c02931c0>] ip_finish_output2+0x0/0x240 (28)
[<c0290a8b>] ip_finish_output+0x26b/0x270 (32)
[<c02931c0>] ip_finish_output2+0x0/0x240 (24)
[<c02931aa>] dst_output+0x1a/0x30 (32)
[<c027dc45>] nf_hook_slow+0xd5/0x130 (12)
[<c0293190>] dst_output+0x0/0x30 (28)
[<c029114a>] ip_queue_xmit+0x45a/0x570 (32)
[<c0293190>] dst_output+0x0/0x30 (24)
[<c0135c75>] sub_preempt_count+0x65/0xd0 (24)
[<c01c79f8>] __up_write+0x148/0x320 (8)
[<c0135708>] check_preempt_timing+0x58/0x2e0 (8)
[<c0135c75>] sub_preempt_count+0x65/0xd0 (4)
[<c01c79f8>] __up_write+0x148/0x320 (4)
[<c0134f9d>] __mcount+0x1d/0x20 (28)
[<c01c727e>] rwsem_owner_del+0xe/0x120 (4)
[<c0134f9d>] __mcount+0x1d/0x20 (52)
[<c02a875e>] tcp_v4_send_check+0xe/0xf0 (4)
[<c02a2259>] tcp_transmit_skb+0x439/0x880 (4)
[<c0114310>] mcount+0x14/0x18 (8)
[<c02a879f>] tcp_v4_send_check+0x4f/0xf0 (20)
[<c02a2302>] tcp_transmit_skb+0x4e2/0x880 (32)
[<c0114310>] mcount+0x14/0x18 (28)
[<c02a4f96>] tcp_send_ack+0xa6/0xf0 (52)
[<c0297ccc>] tcp_recvmsg+0x2ec/0x750 (36)
[<c0134f9d>] __mcount+0x1d/0x20 (20)
[<c0114310>] mcount+0x14/0x18 (44)
[<c026bb59>] sock_common_recvmsg+0x59/0x70 (20)
[<c0267f78>] sock_aio_read+0xf8/0x110 (48)
[<c0114310>] mcount+0x14/0x18 (100)
[<c015e7fa>] do_sync_read+0xaa/0xe0 (20)
[<c01344a0>] autoremove_wake_function+0x0/0x60 (116)
[<c01c11b8>] dummy_file_permission+0x8/0x10 (12)
[<c015e8d6>] vfs_read+0xa6/0x140 (4)
[<c015e933>] vfs_read+0x103/0x140 (36)
[<c0114310>] mcount+0x14/0x18 (24)
[<c015ebe0>] sys_read+0x50/0x80 (20)
[<c010527b>] syscall_call+0x7/0xb (44)
preempt count: 00000002
. 2-level deep critical section nesting:
.. entry 1: down_write+0x249/0x250 [<c02cba99>] / (down_read+0x39/0x50 [<c02cb839>])
.. entry 2: print_traces+0x1d/0x90 [<c0135fcd>] / (dump_stack+0x23/0x30 [<c01060b3>])

BUG: circular semaphore deadlock: ksoftirqd/0/2 is blocked on c0430840, deadlocking links/4724
f7c2be00 00000046 f7c24020 c03bfd60 00000202 00001db4 f7c2a000 f7c24020
f7c24020 f7c2bdec 00000227 e443e1ce 0000001d f7c24020 f7c242b4 f7c2a000
f7c24020 f7c24020 f7c2be24 c02ca79f f7c2be24 00000086 c03e3b00 c02cb9d0
Call Trace:
[<c02ca79f>] schedule+0x2f/0xe0 (80)
[<c02cb9d0>] down_write+0x180/0x250 (16)
[<c02cb9b1>] down_write+0x161/0x250 (20)
[<c02cb839>] down_read+0x39/0x50 (48)
[<c0114310>] mcount+0x14/0x18 (12)
[<c027db97>] nf_hook_slow+0x27/0x130 (28)
[<c0134f9d>] __mcount+0x1d/0x20 (24)
[<c028d4ee>] ip_rcv+0xe/0x540 (4)
[<c027274d>] netif_receive_skb+0x12d/0x240 (4)
[<c0114310>] mcount+0x14/0x18 (8)
[<c028d940>] ip_rcv+0x460/0x540 (20)
[<c028dbc0>] ip_rcv_finish+0x0/0x300 (24)
[<c0114310>] mcount+0x14/0x18 (8)
[<c027274d>] netif_receive_skb+0x12d/0x240 (28)
[<c0270008>] gnet_stats_start_copy+0x18/0x40 (20)
[<c0272a7f>] net_rx_action+0x7f/0x1a0 (4)
[<c0114310>] mcount+0x14/0x18 (8)
[<c02728e8>] process_backlog+0x88/0x1a0 (20)
[<c0272a7f>] net_rx_action+0x7f/0x1a0 (40)
[<c01237c7>] ___do_softirq+0x87/0xd0 (36)
[<c0123898>] _do_softirq+0x8/0x30 (8)
[<c0123c84>] ksoftirqd+0xb4/0x100 (4)
[<c01238b0>] _do_softirq+0x20/0x30 (28)
[<c0123c84>] ksoftirqd+0xb4/0x100 (8)
[<c0133eea>] kthread+0xaa/0xb0 (24)
[<c0123bd0>] ksoftirqd+0x0/0x100 (20)
[<c0133e40>] kthread+0x0/0xb0 (12)
[<c0103319>] kernel_thread_helper+0x5/0xc (16)
preempt count: 00000002
. 2-level deep critical section nesting:
.. entry 1: __schedule+0x4e/0x5f0 [<c02ca1ce>] / (schedule+0x2f/0xe0 [<c02ca79f>])
.. entry 2: __schedule+0xdd/0x5f0 [<c02ca25d>] / (schedule+0x2f/0xe0 [<c02ca79f>])


Michal
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