Re: [PATCH v2 0/9] mm: zone & pgdat accessors plus some cleanup

From: Andrew Morton
Date: Fri Feb 01 2013 - 19:39:33 EST


On Thu, 17 Jan 2013 14:52:52 -0800
Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx> wrote:

> Summaries:
> 1 - avoid repeating checks for section in page flags by adding a define.
> 2 - add & switch to zone_end_pfn() and zone_spans_pfn()
> 3 - adds zone_is_initialized() & zone_is_empty()
> 4 - adds a VM_BUG using zone_is_initialized() in __free_one_page()
> 5 - add pgdat_end_pfn() and pgdat_is_empty()
> 6 - add debugging message to VM_BUG check.
> 7 - add ensure_zone_is_initialized() (for memory_hotplug)
> 8 - use the above addition in memory_hotplug
> 9 - use pgdat_end_pfn()

Well that's a nice little patchset.

Some of the patches were marked From:cody@xxxxxxxxxxxxxxxxxx and others
were From:jmesmon@xxxxxxxxxx This is strange. If you want me to fix
that up, please let me know which is preferred.

> As a general concern: spanned_pages & start_pfn (in pgdat & zone) are supposed
> to be locked (via a seqlock) when read (due to changes to them via
> memory_hotplug), but very few (only 1?) of their users appear to actually lock
> them.

OK, thanks. Perhaps this is something which the memory-hotplug
developers could take a look at?

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