Re: soft lockup - CPU#0 stuck - Kernel 3.17.2

[Patrick Schmid <schmid@phys.ethz.ch>]

On 15.11.2014 00:47, Chris Mason wrote:
> 
> Ok, I think this is related to the new fair read/writer lock 
> implementation in the generic kernel code.  btrfs_clear_path_blocking() 
> will end up taking locks outside of the strict locking order the rest 
> of Btrfs uses.  This used to be fine because we hold the blocking lock 
> while we do it, but with the new queued locks we're running into 
> trouble.  We hit a similar bug earlier and I convinced myself the 
> problem was only with btrfs_next_leaf and our trylock.  But it's a 
> bigger problem than I realized.
> 
> So for now I've changed btrfs_clear_path_blocking to honor the rules 
> and fixed up our trylock to make it faster.
> 
> I'm letting a test run on this patch over the weekend, since I don't 
> want any surprises with your backup farm.
> 
> -chris

Hi Chris

Here comes a short feedback.... I applied your patch (Fix lockups from
btrfs_clear_path_blocking) yesterday and my system survived this night! ;-)

Thank you for the quick fix.

Regards Patrick
-- 
Patrick Schmid  <schmid@phys.ethz.ch>     support: +41 44 633 2668
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