Re: [PATCH] [4/4] SLAB: Fix node add timer race in cache_reap

David Rientjes
2010-02-25T08:01:41Z

On Thu, 25 Feb 2010, Pekka Enberg wrote:

> > > > > I'm just worried there is still an underlying problem here.
> > > > So am I. What caused the breakage that requires this patchset?
> > > Memory hotadd with a new node being onlined.
> >
> > That used to work fine.
>
> OK, can we get this issue resolved? The merge window is open and Christoph
> seems to be unhappy with the whole patch queue. I'd hate this bug fix to miss
> .34...
>

I don't see how memory hotadd with a new node being onlined could have
worked fine before since slab lacked any memory hotplug notifier until
Andi just added it.

That said, I think the first and fourth patch in this series may be
unnecessary if slab's notifier were to call slab_node_prepare() on
MEM_GOING_ONLINE instead of MEM_ONLINE. Otherwise, kswapd is already
running, the zonelists for the new pgdat have been initialized, and the
bit has been set in node_states[N_HIGH_MEMORY] without allocated
cachep->nodelists[node] memory.