Re: race with i_flock?

[Andrew Morton <akpm@zip.com.au>]

Dave Hansen wrote:
> 
> I've been getting some funny freezes while running Specweb.  I don't
> think this is the cause, but I did run into it.
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0xc0147540 in may_open (nd=0xdaa69f78, acc_mode=6, flag=3)
>      at /home/dave/oprofile/linux-2.5.25/include/linux/fs.h:1047
> 
> which is:
> static inline int get_lease(struct inode *inode, unsigned int mode)
> {
> ------->if (inode->i_flock && (inode->i_flock->fl_flags & FL_LEASE))
>                  return __get_lease(inode, mode);
>          return 0;
> }

I get that on about every 1000th reboot (ie: once a week ;))

I have a poke around in kgdb when it happens and everything
looks just fine.  So what must be happening is that some
other CPU has come in and fixed up the pointer before the
kgdb stub captured that CPU.

I'll grab a trace next time.

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