Messages in this thread | | | Subject | Re: setup_per_zone_pages_min(): zone->lock vs. zone->lru_lock | From | Gerald Schaefer <> | Date | Mon, 29 Sep 2008 23:20:05 +0200 |
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On Mon, 2008-09-29 at 18:36 +0100, Andy Whitcroft wrote: > The allocator protects it freelists using zone->lock (as we can see in > rmqueue_bulk), so anything which manipulates those should also be using > that lock. move_freepages() is scanning the cmap and picking up free > pages directly off the free lists, it is expecting those lists to be > stable; it would appear to need zone->lock. It does look like > setup_per_zone_pages_min() is holding the wrong thing at first look.
I just noticed that the spin_lock in that function is much older than the call to setup_zone_migrate_reserve(), which then calls move_freepages(). So it seems that the zone->lru_lock there does (did?) have another purpose, maybe protecting zone->present_pages/pages_min/etc.
Looks like the need for a zone->lock (if any) was added later, but I'm not sure if makes sense to take both locks together, or if the lru_lock is still needed at all.
Thanks, Gerald
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