Messages in this thread | | | Date | Tue, 4 Feb 2014 16:14:07 -0800 (PST) | From | David Rientjes <> | Subject | Re: [patch] mm, page_alloc: make first_page visible before PageTail |
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On Tue, 4 Feb 2014, Andrew Morton 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! >
Ok.
> > Reported-by: Holger Kiehl <Holger.Kiehl@dwd.de> > > What did Holger report? >
A once-in-five-years NULL pointer dereference on the aforementioned page_count(page).
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