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Date: Wed, 19 Jan 2005 17:01:23 -0500 (EST)
From: linux-os <linux-os@analogic.com>
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To: Andrew Morton <akpm@osdl.org>
cc: Badari Pulavarty <pbadari@us.ibm.com>, linux-kernel@vger.kernel.org
Subject: Re: 2.6.10-mm1 hang
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 <20050119133136.7a1c0454.akpm@osdl.org>
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On Wed, 19 Jan 2005, Andrew Morton wrote:

> Badari Pulavarty <pbadari@us.ibm.com> wrote:
>>
>> I was playing with kexec+kdump and ran into this on 2.6.10-mm1.
>>  I have seen similar behaviour on 2.6.10.
>>
>>  I am using a 4-way P-III machine. I have a module which tries
>>  gets same spinlock twice. When I try to "insmod" this module,
>>  my system hangs. All my windows froze, no more new logins,
>>  console froze, doesn't respond to sysrq. I wasn't expecting
>>  a system hang. Why ? Ideas ?
>>
>
> Maybe all the other CPUs are stuck trying to send an IPI to this one?  An
> NMI watchdog trace would tell.
>
>>  #include <linux/init.h>
>>  #include <asm/uaccess.h>
>>  #include <linux/spinlock.h>
>>  spinlock_t mylock = SPIN_LOCK_UNLOCKED;
>>  static int __init panic_init(void)
>>  {
>>          spin_lock_irq(&mylock);
>>          spin_lock_irq(&mylock);
>>         return 1;
>>  }
> -

What would you expect this to do? After the first lock is
obtained, the second MUST fail forever or else the spin-lock
doesn't work. The code, above, just proves that spin-locks
work!


Cheers,
Dick Johnson
Penguin : Linux version 2.6.10 on an i686 machine (5537.79 BogoMips).
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