On Fri, Aug 05, 2016 at 12:55:26PM +0100, Mel Gorman wrote:

On Fri, Aug 05, 2016 at 11:52:57AM +0100, James Hogan wrote:

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What's surprising is that it worked for the zone stats as it appears
that calling zone_reclaimable() from that context should also have
broken. Did anything change recently that would have avoided the
zone->pageset dereference in zone_reclaimable() before?

It appears that zone_pcp_init() was already setting zone->pageset to
&boot_pageset, via paging_init():

/me slaps self

Of course.

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The easiest option would be to not call show_mem from arch code until
after the pagesets are setup.

Since no other arches seem to do show_mem earily during boot like metag,
and doing so doesn't really add much value, I'm happy to remove it
anyway.

Thanks. Can I assume you'll merge such a patch or should I roll one?

Yep, I'll take care of it.

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However could your change break other things and need fixing anyway?

Not that I'm aware of. There would have to be a node-based stat that has
meaning that early in boot to have an effect. If one happened to added
then it would need fixing but until then the complexity is unnecessary.

Okay, thanks for the help,

Cheers
James