Do we need to fix below dump during cpu hot plug operation?

[Peter Chen]

Hi all,

When doing system suspend/resume or CPU hot plug at SMP platform (like 
Freescale i.mx6Q sabrelite board), if local time is enabled, 
there is a clk_get_rate at twd_timer_setup during the atomic context.
So, if mutex_lock debug is enabled, there will be below dump message.
Although it will not affect future system use, it is boring message.

BUG: sleeping function called from invalid context at /home/b29397/work/code/git/linus/linux-2.6/kernel/mutex.c:269
no locks held by swapper/1/0.
irq event stamp: 279320
hardirqs last  enabled at (279319): [<80052bd0>] idle_task_exit+0x16c/0x1a0
hardirqs last disabled at (279320): [<8051a470>] cpu_die+0x28/0x98
softirqs last  enabled at (279304): [<8002ae3c>] _local_bh_enable+0x14/0x18
softirqs last disabled at (279303): [<8002aea8>] irq_enter+0x68/0x78
Backtrace: 
[<8001284c>] (dump_backtrace+0x0/0x10c) from [<8052b614>] (dump_stack+0x18/0x1c)
 r7:8062b070 r6:0000010d r5:00000000 r4:bf88c000
[<8052b5fc>] (dump_stack+0x0/0x1c) from [<80050bb4>] (__might_sleep+0x1ec/0x238)
[<800509c8>] (__might_sleep+0x0/0x238) from [<8052cf60>] (mutex_lock_nested+0x38/0x3bc)
 r7:00000000 r6:bf88c000 r5:808b19e0 r4:808a5360
[<8052cf28>] (mutex_lock_nested+0x0/0x3bc) from [<803e2108>] (clk_get_rate+0x1c/0x84)
[<803e20ec>] (clk_get_rate+0x0/0x84) from [<8052900c>] (twd_timer_setup+0x28c/0x2e0)
 r5:808b19e0 r4:817c0200
[<80528d80>] (twd_timer_setup+0x0/0x2e0) from [<805288b8>] (percpu_timer_setup+0x6c/0xdc)
 r9:412fc09a r8:1000406a r7:808b19d8 r6:bf88c000 r5:80879c14
r4:817c0200
[<8052884c>] (percpu_timer_setup+0x0/0xdc) from [<80528a68>] (secondary_start_kernel+0x140/0x19c)
 r5:80879c14 r4:00000001
[<80528928>] (secondary_start_kernel+0x0/0x19c) from [<10528248>] (0x10528248)
 r7:808b19d8 r6:10c03c7d r5:0000001f r4:4f87806a
BUG: scheduling while atomic: swapper/1/0/0x40000002
no locks held by swapper/1/0.
Modules linked in:
irq event stamp: 279320
hardirqs last  enabled at (279319): [<80052bd0>] idle_task_exit+0x16c/0x1a0
hardirqs last disabled at (279320): [<8051a470>] cpu_die+0x28/0x98
softirqs last  enabled at (279304): [<8002ae3c>] _local_bh_enable+0x14/0x18
softirqs last disabled at (279303): [<8002aea8>] irq_enter+0x68/0x78
Backtrace: 
[<8001284c>] (dump_backtrace+0x0/0x10c) from [<8052b614>] (dump_stack+0x18/0x1c)
 r7:00000001 r6:bf88c000 r5:bf890000 r4:bf890000
[<8052b5fc>] (dump_stack+0x0/0x1c) from [<800539b4>] (__schedule_bug+0x5c/0x7c)
[<80053958>] (__schedule_bug+0x0/0x7c) from [<8052e1a8>] (__schedule+0x620/0x6e0)
 r5:bf890000 r4:819215c0
[<8052db88>] (__schedule+0x0/0x6e0) from [<8052e320>] (_cond_resched+0x44/0x58)
[<8052e2dc>] (_cond_resched+0x0/0x58) from [<8052cf64>] (mutex_lock_nested+0x3c/0x3bc)
 r5:808b19e0 r4:808a5360
[<8052cf28>] (mutex_lock_nested+0x0/0x3bc) from [<803e2108>] (clk_get_rate+0x1c/0x84)
[<803e20ec>] (clk_get_rate+0x0/0x84) from [<8052900c>] (twd_timer_setup+0x28c/0x2e0)
 r5:808b19e0 r4:817c0200
[<80528d80>] (twd_timer_setup+0x0/0x2e0) from [<805288b8>] (percpu_timer_setup+0x6c/0xdc)
 r9:412fc09a r8:1000406a r7:808b19d8 r6:bf88c000 r5:80879c14
r4:817c0200
[<8052884c>] (percpu_timer_setup+0x0/0xdc) from [<80528a68>] (secondary_start_kernel+0x140/0x19c)
 r5:80879c14 r4:00000001
[<80528928>] (secondary_start_kernel+0x0/0x19c) from [<10528248>] (0x10528248)
 r7:808b19d8 r6:10c03c7d r5:0000001f r4:4f87806a

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Best Regards,
Peter Chen