Re: 2.6.34-rc5-git6 (plus all patches) -- new INFO: suspiciousrcu_dereference_check() usage.

From: Paul E. McKenney
Date: Mon Apr 26 2010 - 12:10:54 EST


On Sun, Apr 25, 2010 at 05:19:38PM -0400, Miles Lane wrote:
> [ 139.730133] [ INFO: suspicious rcu_dereference_check() usage. ]
> [ 139.730136] ---------------------------------------------------
> [ 139.730139] include/net/inet_timewait_sock.h:227 invoked
> rcu_dereference_check() without protection!
> [ 139.730142]
> [ 139.730143] other info that might help us debug this:
> [ 139.730144]
> [ 139.730147]
> [ 139.730148] rcu_scheduler_active = 1, debug_locks = 1
> [ 139.730151] 1 lock held by swapper/0:
> [ 139.730158] #0: (net/ipv4/tcp_minisocks.c:41){+.-...}, at:
> [<ffffffff81046ad2>] run_timer_softirq+0x19f/0x370
> [ 139.730169]
> [ 139.730170] stack backtrace:
> [ 139.730173] Pid: 0, comm: swapper Not tainted 2.6.34-rc5-git6 #28
> [ 139.730176] Call Trace:
> [ 139.730178] <IRQ> [<ffffffff81065f9a>] lockdep_rcu_dereference+0x9d/0xa5
> [ 139.730189] [<ffffffff813d1abf>] twsk_net+0x4f/0x57
> [ 139.730193] [<ffffffff813d2122>] __inet_twsk_kill+0x79/0xd0
> [ 139.730198] [<ffffffff813d24f9>] inet_twdr_do_twkill_work+0x59/0xba
> [ 139.730203] [<ffffffff813d263d>] inet_twdr_hangman+0x30/0x97
> [ 139.730207] [<ffffffff81046b9e>] run_timer_softirq+0x26b/0x370
> [ 139.730211] [<ffffffff81046ad2>] ? run_timer_softirq+0x19f/0x370
> [ 139.730216] [<ffffffff813d260d>] ? inet_twdr_hangman+0x0/0x97
> [ 139.730221] [<ffffffff81040230>] ? __do_softirq+0x7f/0x252
> [ 139.730225] [<ffffffff810402f5>] __do_softirq+0x144/0x252
> [ 139.730230] [<ffffffff8100320c>] call_softirq+0x1c/0x34
> [ 139.730235] [<ffffffff81004864>] do_softirq+0x38/0x80
> [ 139.730239] [<ffffffff8103fdc2>] irq_exit+0x45/0x94
> [ 139.730243] [<ffffffff81003fa9>] do_IRQ+0xad/0xc4
> [ 139.730247] [<ffffffff81432953>] ret_from_intr+0x0/0xf
> [ 139.730250] <EOI> [<ffffffff81248383>] ? acpi_idle_enter_bm+0x262/0x28d
> [ 139.730260] [<ffffffff81248379>] ? acpi_idle_enter_bm+0x258/0x28d
> [ 139.730266] [<ffffffff8137b9cf>] cpuidle_idle_call+0x9c/0x13d
> [ 139.730273] [<ffffffff810012c2>] cpu_idle+0xa5/0xfc
> [ 139.730277] [<ffffffff8142abdd>] start_secondary+0x1f3/0x1fc

This appears to be another symptom of the bug you located in your earlier
testing, so either Eric Biederman sends a patch or I improvise.

And thank you again for all your testing, Miles!!!

Thanx, Paul
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