On Wed, 19 Jan 2005, Andrew Morton wrote:

Badari Pulavarty <[EMAIL PROTECTED]> 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!


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