Re: [fixed] [patch] Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+

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Cc: <mingo@...>, <mcmanus@...>, <peterz@...>, <linux-kernel@...>, <netdev@...>, <rjw@...>, <akpm@...>, <johnpol@...>
Date: Tuesday, June 10, 2008 - 6:32 pm

From: "Ilpo_Järvinen" <ilpo.jarvinen@helsinki.fi>
Date: Wed, 4 Jun 2008 02:22:16 +0300 (EEST)


I took a close look at this, it seems this patch adds
an ABBA deadlock.  But I might be wrong.

Normally the locking order is:

	listen_sk --> some_child_sk

And this can be seen by the code paths that flow down
to tcp_child_process() in net/ipv4/tcp_minisocks.c (via
tcp_v4_do_rcv() for example).

However here in this patch we will lock in the:

	child_sk --> listen_sk

order.

Unless... these defer accepted sockets live outside of the
normal socket collection found by tcp_v{4,6}_hnd_req().  If
that is the case, that ought to make this locking order OK
but I fear that lockdep will likely complain because it has
no way to see this distinction.

If we cannot find a simple and easy way to deal with this locking
problem, I am reverting the defer-accept changes entirely.  It's not
the end of the world if this feature has to be deferred to 2.6.27
and this bug has been known for several weeks already.

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Messages in current thread:
[bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Mon May 26, 7:56 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Thu May 29, 7:14 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 7:46 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 8:18 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 8:58 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Sat May 31, 12:35 pm)
Re: [fixed] [patch] Re: [bug] stuck localhost TCP connection..., David Miller, (Tue Jun 10, 6:32 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Patrick McManus, (Sat May 31, 6:46 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sun Jun 1, 1:51 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Fri May 30, 5:12 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Thu May 29, 9:48 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Evgeniy Polyakov, (Thu May 29, 9:05 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Peter Zijlstra, (Wed May 28, 5:27 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Sat May 31, 10:25 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 12:09 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Sat May 31, 1:58 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 2:37 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Sat May 31, 4:25 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 5:39 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Tue Jun 3, 8:10 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Wed Jun 4, 7:14 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Wed Jun 4, 10:00 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Wed Jun 4, 11:09 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Fri Jun 6, 5:32 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon Jun 9, 3:24 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Tue Jun 10, 7:26 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Wed Jun 11, 9:39 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Wed Jun 18, 8:30 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Håkon Løvdal, (Sat May 31, 5:45 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Sat May 31, 1:22 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Arjan van de Ven, (Mon May 26, 12:24 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon May 26, 9:28 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Mon May 26, 10:12 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon May 26, 10:58 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Mon May 26, 12:23 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon May 26, 12:32 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Mon May 26, 12:54 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon May 26, 1:08 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon May 26, 5:20 pm)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Mon May 26, 10:17 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ilpo Järvinen, (Mon May 26, 10:43 am)
Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+, Ingo Molnar, (Mon May 26, 10:29 am)