Re: 2.6.23-rc2-mm1: sleeping function called from invalid contextat kernel/mutex.c:86

[Andrew Morton]

On Fri, 10 Aug 2007 01:23:07 +0200
Mariusz Kozlowski <m.kozlowski@xxxxxxxxxx> wrote:

> Hello,
> 
> 	This probably doesn't have great impact ;) but ...
> To reproduce: run torture tests for RCU and then sysrq+q.
> 
> SysRq : Show Pending Timers
> Timer List Version: v0.3
> HRTIMER_MAX_CLOCK_BASES: 2
> now at 1764338760370 nsecs
> 
> cpu: 0
>  clock 0:
>   .index:      0
>   .resolution: 1 nsecs
>   .get_time:   ktime_get_real
>   .offset:     1186699025823815427 nsecs
> active timers:
>  clock 1:
>   .index:      1
>   .resolution: 1 nsecs
>   .get_time:   ktime_get
>   .offset:     0 nsecs
> active timers:
>  #0: <3>BUG: sleeping function called from invalid context at kernel/mutex.c:86
> in_atomic():1, irqs_disabled():1
> INFO: lockdep is turned off.
> irq event stamp: 0
> hardirqs last  enabled at (0): [<00000000>] 0x0
> hardirqs last disabled at (0): [<c0117def>] copy_process+0x4a8/0x144c
> softirqs last  enabled at (0): [<c0117e0d>] copy_process+0x4c6/0x144c
> softirqs last disabled at (0): [<00000000>] 0x0
>  [<c0104869>] show_trace_log_lvl+0x1a/0x30
>  [<c01053ad>] show_trace+0x12/0x14
>  [<c0105515>] dump_stack+0x15/0x17
>  [<c0114da7>] __might_sleep+0xb7/0xc9
>  [<c0451771>] mutex_lock+0x15/0x1f
>  [<c0141b75>] lookup_module_symbol_name+0x17/0xc0
>  [<c014272a>] lookup_symbol_name+0x3f/0x43
>  [<c013287e>] print_name_offset+0x1f/0x96
>  [<c01330f7>] timer_list_show+0x802/0xcbd
>  [<c01335be>] sysrq_timer_list_show+0xc/0xe
>  [<c02cc4a1>] sysrq_handle_show_timers+0x8/0xa
>  [<c02cc3ac>] __handle_sysrq+0x7b/0x115
>  [<c02cc466>] handle_sysrq+0x20/0x24
>  [<c02c69c1>] kbd_event+0x3a8/0x5c7
>  [<c0362f8f>] input_pass_event+0x8f/0x91
>  [<c0363e77>] input_handle_event+0x98/0x38d
>  [<c0364e6d>] input_event+0x54/0x67
>  [<c03682c2>] atkbd_interrupt+0x200/0x59e
>  [<c0360cd0>] serio_interrupt+0x7c/0x80
>  [<c0361965>] i8042_interrupt+0x17a/0x289
>  [<c0147a5d>] handle_IRQ_event+0x28/0x59
>  [<c01493ca>] handle_level_irq+0xad/0x10b
>  [<c0105a13>] do_IRQ+0x93/0xd0
>  [<c010441e>] common_interrupt+0x2e/0x34
>  [<df39d7e3>] rcu_read_delay+0x8/0x36 [rcutorture]
>  [<df39d99a>] rcu_torture_reader+0x6e/0x169 [rcutorture]
>  [<c012c11e>] kthread+0x36/0x58
>  [<c010451b>] kernel_thread_helper+0x7/0x1c
>  =======================

We seem to have made a mess in there.  timer_list_show() ends up calling
lookup_module_symbol_name(), which takes a mutex.  However print_symbol()
(which is called at oops time, interrupt time, etc) calls
module_address_lookup(), which is basically the same, only it doesn't take
the mutex.

I guess a quicky fix would be to switch
kernel/time/timer_list.c:print_name_offset() from
lookup_module_symbol_name() to module_address_lookup().  But we'd still
have a mess in there.

(adds ccs, runs away)

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