Re: kernel BUG at linux-3.16.7-ckt25/fs/dcache.c:2373!

[J. Bruce Fields]

On Fri, Jun 03, 2016 at 11:17:16AM +0200, Philipp Hahn wrote:
> Hello,
> 
> Am 02.06.2016 um 22:02 schrieb J. Bruce Fields:
> > On Thu, Jun 02, 2016 at 09:51:27AM +0200, Philipp Hahn wrote:
> >> probably during heavy IO our file server crashed on a BUG_ON in dache.c,
> >> probably triggered by NFS:
> >>
> >>> ------------[ cut here ]------------
> >>> kernel BUG at /var/build/temp/tmp.BPql4ErveJ/pbuilder/linux-3.16.7-ckt25/fs/dcache.c:2373!
> ...
> >> Our kernel is 3.16.7-ckt25 from Debian + ckt26 and ckt27 on top.
> > 
> > So this is the BUG_ON(!d_unhashed(..)) at the top of __d_rehash?  I
> > don't know the -ckt kernels, and I don't have a BUG at line 2373 of
> > dcache.c, or something else?
> 
> Yes, exactly that first line.

Oh, from googling... it looks like that's what they're calling the
Ubuntu kernels these days?  It'd be best to have them triage this first.

> > There have been a lot of changes in the area since 3.16.7.
> 
> Too bad.
> Any concrete hint or should I better spent my time convincing management
> to install a newer Linux kernel?

I don't know if a newer kernel's better, but if you were able to
reproduce this frequently then experimenting with different kernel
versions might be one way to work this out.

I suppose 75a2352d0110960aeee1a28ddc09a55f97c99100 might in theory be a
fix?  Not a tall sure of that, though.

--b.

> 
> Anyway, thank you for the response.
> 
> Philipp