Re: [PATCH] hibernate / memory hotplug: always use for_each_populated_zone()

[KOSAKI Motohiro]

> From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
> 
> Use for_each_populated_zone() instead of for_each_zone() in hibernation
> code. This fixes a bug on s390, where we allow both config options
> HIBERNATION and MEMORY_HOTPLUG, so that we also have a ZONE_MOVABLE
> here. We only allow hibernation if no memory hotplug operation was
> performed, so in fact both features can only be used exclusively, but
> this way we don't need 2 differently configured (distribution) kernels.
> 
> If we have an unpopulated ZONE_MOVABLE, we allow hibernation but run
> into a BUG_ON() in memory_bm_test/set/clear_bit() because hibernation
> code iterates through all zones, not only the populated zones, in
> several places. For example, swsusp_free() does for_each_zone() and
> then checks for pfn_valid(), which is true even if the zone is not
> populated, resulting in a BUG_ON() later because the pfn cannot be
> found in the memory bitmap.
> 
> Replacing all occurences of for_each_zone() in hibernation code with
> for_each_populated_zone() would fix this issue.
> 
> Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>

Thanks this effort.
	Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>



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