Re: lockup on Athlon systems, kernel race condition?

From: Andrew Morton (akpm@zip.com.au)
Date: Fri Aug 30 2002 - 16:15:14 EST


Terence Ripperda wrote:
>
> ...
>
> asmlinkage long sys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg)
> {
> struct file * filp;
> unsigned int flag;
> int on, error = -EBADF;
>
> filp = fget(fd);
> if (!filp)
> goto out;
> error = 0;
> lock_kernel(); <====
> switch (cmd) {

This CPU is spinning, waiting for kernel_flag. It will take the IPI
and the other CPU's smp_call_function() will succeed.

Possibly the IPI has got lost - seems that this is a popular failure mode
for flakey chipsets/motherboards.

Or someone has called sys_ioctl() with interrupts disabled. That's very
doubtful.
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