Re: [PATCH 6/6]suspend/resume SMP support

Re: [PATCH 6/6]suspend/resume SMP support

[Andrew Morton]

Li Shaohua <shaohua.li@intel.com> wrote:
>
> CPU0 attaching NULL sched-domain.
> CPU1 attaching NULL sched-domain.
> CPU0 attaching NULL sched-domain.
> Booting processor 1/1 eip 3000
> Initializing CPU#1
> masked ExtINT on CPU#1
> Unable to handle kernel paging request at virtual address f000acb2
>  printing eip:
> c014e4cc
> *pde = 00000000
> Oops: 0000 [#1]
> PREEMPT SMP 
> Modules linked in:
> CPU:    1
> EIP:    0060:[<c014e4cc>]    Not tainted VLI
> EFLAGS: 00010097   (2.6.12-rc2-mm3) 
> EIP is at check_poison_obj+0x4c/0x1e0
> eax: 0000006b   ebx: 0000005a   ecx: dff6e080   edx: dff6e480
> esi: 00000000   edi: f000acb2   ebp: 00000080   esp: c14fdcd4
> ds: 007b   es: 007b   ss: 0068
> Process swapper (pid: 0, threadinfo=c14fc000 task=dff42560)
> Stack: dff6e480 5a5a5a5a 5a5a5a5a 0000007f 5a5a5a5a 00000000 0000005a f000acae 
>        dff6e480 c021192e c0150031 dff6e480 f000acae 5a5a5a5a 5a5a5a5a dff6e480 
>        00000046 00000020 00000010 c015044b dff6e480 00000020 f000acae c021192e 
> Call Trace:
>  [<c021192e>] soft_cursor+0x5e/0x260
>  [<c0150031>] cache_alloc_debugcheck_after+0x181/0x1a0
>  [<c015044b>] __kmalloc+0x9b/0xd0
>  [<c021192e>] soft_cursor+0x5e/0x260
>  [<c021192e>] soft_cursor+0x5e/0x260
>  [<c020a459>] bit_cursor+0x339/0x540
>  [<c0118998>] recalc_task_prio+0x88/0x150
>  [<c0205c32>] fbcon_cursor+0x1a2/0x270
>  [<c0265475>] hide_cursor+0x25/0x40
>  [<c026843a>] vt_console_print+0x2aa/0x2b0
>  [<c0120d32>] __call_console_drivers+0x62/0x70
>  [<c0120e66>] call_console_drivers+0x96/0x130
>  [<c0121361>] release_console_sem+0x51/0xc0
>  [<c01211df>] vprintk+0x19f/0x250
>  [<c01264b6>] __do_softirq+0xd6/0xf0
>  [<c0438f5b>] preempt_schedule_irq+0x4b/0x80
>  [<c0121037>] printk+0x17/0x20
>  [<c0114132>] setup_local_APIC+0xe2/0x1d0
>  [<c01130ba>] smp_callin+0x7a/0x120
>  [<c011316e>] start_secondary+0xe/0x190
> Code: 24 30 89 14 24 01 c7 e8 13 f8 ff ff 39 44 24 14 89 c5 0f 8d b7 00 00 00 8d 40 ff 89 44 24 0c 3b 74 24 0c b0 6b 0f 84 8c 01 00 00 <38> 04 3e 74 46 8b 44 24 14 85 c0 0f 84 48 01 00 00 89 3c 24 83 
>  <0>Kernel panic - not syncing: Attempted to kill the idle task!
>

fbcon is trying to call kmalloc before the slab system is initialised. 
It would be best to fix that within fbcon.


> > Code: d2 74 bd fc 8b 44 24 28 b9 0e 00 00 00 8b 74 24 14 01 c6 b8 0e
> > 00 00 00 89 74 24 1c 8b 74 24 30 89 44 24 10 8b 7c 24 1c 83 c6 10 <f3>
> > a5 8b 74 24 24 8b 44 24 1c 89 4c 24 10 01 ee f7 d5 21 ee 89
> >  <0>Kernel panic - not syncing: Attempted to kill the idle task!
> >  Stuck ??
> > Inquiring remote APIC #0...
> > ... APIC #0 ID: 00000000
> > ... APIC #0 VERSION: 00040011
> > ... APIC #0 SPIV: 000000ff
> > root@hobit:/sys/devices/system/cpu/cpu1#
> Andrew,
> Below patch fixed Pavel's oops. But strange is the 'system_state' check
> is added for CPU hotplug by Rusty. This really makes me confused. Could
> you please look at it.

Well as the comment says, if this CPU isn't online yet, and if the system
has not yet reached SYSTEM_RUNNING state then we bale out of the printk
because this cpu's per-cpu resources may not yet be fully set up.


> This can be reproduced 100% with radeonfb driver load. Attached is the
> dmesg of an oops. It seems the 'objp' parameter for
> 'cache_alloc_debugcheck_after' is invalid.
> 
> --- a/kernel/printk.c	2005-04-12 10:12:19.000000000 +0800
> +++ b/kernel/printk.c	2005-04-13 17:22:40.912897328 +0800
> @@ -624,8 +624,7 @@ asmlinkage int vprintk(const char *fmt, 
>  			log_level_unknown = 1;
>  	}
>  
> -	if (!cpu_online(smp_processor_id()) &&
> -	    system_state != SYSTEM_RUNNING) {
> +	if (!cpu_online(smp_processor_id())) {
>  		/*
>  		 * Some console drivers may assume that per-cpu resources have
>  		 * been allocated.  So don't allow them to be called by this
> 

That being said, I don't see why your patch should fix the oops.  The test
(system_state != SYSTEM_RUNNING) should be returning true at this time.




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Re: [PATCH 6/6]suspend/resume SMP support

[Pavel Machek]

Hi!

> > > Code: d2 74 bd fc 8b 44 24 28 b9 0e 00 00 00 8b 74 24 14 01 c6 b8 0e
> > > 00 00 00 89 74 24 1c 8b 74 24 30 89 44 24 10 8b 7c 24 1c 83 c6 10 <f3>
> > > a5 8b 74 24 24 8b 44 24 1c 89 4c 24 10 01 ee f7 d5 21 ee 89
> > >  <0>Kernel panic - not syncing: Attempted to kill the idle task!
> > >  Stuck ??
> > > Inquiring remote APIC #0...
> > > ... APIC #0 ID: 00000000
> > > ... APIC #0 VERSION: 00040011
> > > ... APIC #0 SPIV: 000000ff
> > > root@hobit:/sys/devices/system/cpu/cpu1#
> > Andrew,
> > Below patch fixed Pavel's oops. But strange is the 'system_state' check
> > is added for CPU hotplug by Rusty. This really makes me confused. Could
> > you please look at it.
> 
> Well as the comment says, if this CPU isn't online yet, and if the system
> has not yet reached SYSTEM_RUNNING state then we bale out of the printk
> because this cpu's per-cpu resources may not yet be fully set up.
> 
> 
> > This can be reproduced 100% with radeonfb driver load. Attached is the
> > dmesg of an oops. It seems the 'objp' parameter for
> > 'cache_alloc_debugcheck_after' is invalid.
> > 
> > --- a/kernel/printk.c	2005-04-12 10:12:19.000000000 +0800
> > +++ b/kernel/printk.c	2005-04-13 17:22:40.912897328 +0800
> > @@ -624,8 +624,7 @@ asmlinkage int vprintk(const char *fmt, 
> >  			log_level_unknown = 1;
> >  	}
> >  
> > -	if (!cpu_online(smp_processor_id()) &&
> > -	    system_state != SYSTEM_RUNNING) {
> > +	if (!cpu_online(smp_processor_id())) {
> >  		/*
> >  		 * Some console drivers may assume that per-cpu resources have
> >  		 * been allocated.  So don't allow them to be called by this
> > 
> 
> That being said, I don't see why your patch should fix the oops.  The test
> (system_state != SYSTEM_RUNNING) should be returning true at this time.

We were booting CPU on running system. system_state was definitely
SYSTEM_RUNNING, but we were trying to bring CPU#1 online...

Check is wrong. If cpu is not yet online, we may not printk on
it... It does not really depend on system_state...

								Pavel
-- 
Boycott Kodak -- for their patent abuse against Java.


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Re: [PATCH 6/6]suspend/resume SMP support

[Li Shaohua]

On Sun, 2005-04-24 at 06:35, Andrew Morton wrote:
> fbcon is trying to call kmalloc before the slab system is initialised. 
> It would be best to fix that within fbcon.
This solves the problem too.

> Well as the comment says, if this CPU isn't online yet, and if the system
> has not yet reached SYSTEM_RUNNING state then we bale out of the printk
> because this cpu's per-cpu resources may not yet be fully set up.
After the CPU is offline (we are doing CPU hotplug). Its per-cpu
resources like kmalloc also aren't initialized. This is in
SYSTEM_RUNNING state too, so the system state doesn't matter. Removing
the system state check seems better than fixing the fbcon driver to me.

Thanks,
Shaohua



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