Re: [BUG] fatal hang untarring 90GB file, possibly writebackrelated.

[James Bottomley]

On Wed, 2011-04-27 at 12:33 -0400, Chris Mason wrote:
> Probably easier to debug with a sysrq-l and sysrq-w. 

Yes, just enabling them for the repro ... I didn't echo 1
> /proc/sys/kernel/sysrq first time around

>  If you get stuck
> on the filesystem, it is probably waiting on ram, which it probably
> can't get because kswapd is spinning.  Eventually everyone backs up
> waiting for the transaction that never ends.  If we're really lucky it
> is just GFP_KERNEL where it should NOFS.
> 
> Since you're often stuck in different spots inside shrink_slab, we're
> probably not stuck on a lock.  But, trying with lock debugging, lockdep
> enabled and preempt on is a good idea to rule out locking mistakes.
> 
> Does the fedora debug kernel enable preempt?

No ... I've taken the Fedora 15 kernel config directly from their
install CD for this (with a bit of munging to get it to work on -rc4)

James


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