Re: [patch] mm, page_alloc: make first_page visible before PageTail

[Andrew Morton]

On Tue, 4 Feb 2014 16:02:39 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote:

> Commit bf6bddf1924e ("mm: introduce compaction and migration for ballooned 
> pages") introduces page_count(page) into memory compaction which 
> dereferences page->first_page if PageTail(page).
> 
> Introduce a store memory barrier to ensure page->first_page is properly 
> initialized so that code that does page_count(page) on pages off the lru 
> always have a valid p->first_page.

Could we have a code comment please?  Even checkpatch knows this rule!

> Reported-by: Holger Kiehl <Holger.Kiehl@xxxxxx>

What did Holger report?

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