[Crash-utility] kernel 4.20-rc1 compatibility - radix tree replaced by xarray

[Dave Anderson]

----- Original Message -----
> Hi,
> 
> just a head's up that the linux radix_tree got replaced by something
> called xarray in 4.20 (already into master, will be in 4.20-rc1)
> 
> You can look at the patch series here:
> https://lore.kernel.org/lkml/20180313132639.17387-3-willy@infradead.org/T/#m6a36aa7f22925c61ed59ed78312ccfadb08f9ecc
> 
> * [PATCH v9 11/61] xarray: Add definition of struct xarray
>  -> replaces radix_tree_root by xarray
> * [PATCH v9 12/61] xarray: Define struct xa_node
>  -> replaces radix_tree_node by xa_node
> 
> As far as I can tell they look fairly close to radix_tree for now, but
> while I hoped just renaming fields and removing max height might do the
> trick, but it looks like one would need to actually look at the
> differences in implementation as just doing that was a bit optimistic...
> The tree iteration for running tasks got me 4 tasks so it obviously
> didn't get very far; I probably missed something obvious.
> 
> 
> For now I wanted to debug something else so went back a notch instead of
> trying harder, I'll probably come back to this in the next few weeks if
> nobody else has. Don't wait for me if you want to do it though :)
> 
> (hopefully that'll save someone a few minutes if they run into this
> meanwhile)
> 

Hi Dominique,

Thanks for the heads-up -- this is a critical change w/respect to
the crash utility, affecting several other parts as well as the
PID/task gathering mechanism.  I don't have access to 4.20-rc1
kernels in-house, or from Fedora, at the moment, so I won't be able
to do any hands-on work on it for a while.  So given the insights
you've gained already, by all means please continue if you can!

Thanks,
  Dave



> 
> Cheers,
> --
> Dominique Martinet | Asmadeus
> 
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