On Tue, 16 Oct 2012, KOSAKI Motohiro wrote:

quoted

quoted

I don't think 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a is right fix.

It's certainly not a complete fix, but I think it's a much better result
of the race, i.e. we don't panic anymore, we simply fail the read()
instead.

Even though 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a itself is simple. It bring
to caller complex. That's not good and have no worth.

Before: the kernel panics, all workloads cease.
After: the file shows garbage, all workloads continue.

This is better, in my opinion, but at best it's only a judgment call and 
has no effect on anything.

I agree it would be better to respect the return value of mpol_to_str() 
since there are other possible error conditions other than a freed 
mempolicy, but let's not consider reverting 80de7c3138.  It is obviously 
not a full solution to the problem, though, and we need to serialize with 
task_lock().

Dave, are you interested in coming up with a patch?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>