On Wed, 30 Mar 2022, Matthew Wilcox wrote:
> On Mon, Mar 28, 2022 at 09:24:00PM -0700, Hugh Dickins wrote:
> > I'm not familiar with workingset.c, I'll make no guesses, over to you!
>
> I haven't been able to reproduce it, but I applied Feynman's Problem
> Solving Algorithm, and I think this will do the trick:
Excellent! Yes, this fixes it - thanks.
Hugh
>
> diff --git a/lib/xarray.c b/lib/xarray.c
> index b95e92598b9c..d3b168f619b1 100644
> --- a/lib/xarray.c
> +++ b/lib/xarray.c
> @@ -1079,6 +1079,7 @@ void xas_split(struct xa_state *xas, void *entry, unsigned int order)
> xa_mk_node(child));
> if (xa_is_value(curr))
> values--;
> + xas_update(xas, child);
> } else {
> unsigned int canon = offset - xas->xa_sibs;
>
> @@ -1093,6 +1094,7 @@ void xas_split(struct xa_state *xas, void *entry, unsigned int order)
> } while (offset-- > xas->xa_offset);
>
> node->nr_values += values;
> + xas_update(xas, node);
> }
> EXPORT_SYMBOL_GPL(xas_split);
> #endif
>
> (the key insight is that the update function should have removed the
> node from the list; the WARN_ON really means "this node should not be on
> the list", so there's somewhere that we're forgetting to call
> xas_update(), or somewhere that we're forgetting to call
> mapping_set_update(). I didn't find any of the latter, but I did find
> one of the former)
