Re: uninterruptible sleep lockups

[Anthony DiSante <theant@nodivisions.com>]

Valdis.Kletnieks@vt.edu wrote:
>>It seems like this problem is always going to exist, because some hardware 
>>and some drivers will always be buggy.  So shouldn't we have some sort of 
>>watchdog higher up in the kernel, that watches for hung processes like this 
>>and kills them?
> 
> And said watchdog would clean up the mess, how, exactly?  There's lots of sticky
> issues having to do with breaking locks and possibly still-pending I/O (I once had
> a tape drive complete an I/O 3 *days* after the request was sent - good thing no
> watchdog killed the process and deallocated the memory that I/O landed in ;)

I'm not a kernel programmer, so I don't have the answers to any of that.  I 
guess I was thinking that there'd be some way to distinguish between 
processes that are truly stuck -- that is, never coming back -- and 
processes like yours, that are taking a long time but still working.

Or maybe it SHOULD have killed your process, in some "proper" way that 
prevents any outstanding I/O requests from coming in days later and breaking 
things.  Again, I'm no kernel hacker, but if an I/O request takes *3 days*, 
isn't that an indication of a bug or of faulty hardware perhaps?

> It's been covered before, look in the lkml archives for details.

Thanks, I'll do that.  But could you give me a more specific pointer? 
Searching lkml for "uninterruptible" returns ~2000 results.

Thanks,
Anthony DiSante
http://nodivisions.com/