lkml.org 
[lkml]   [2014]   [Feb]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] mm, page_alloc: make first_page visible before PageTail
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).


\
 
 \ /
  Last update: 2014-02-05 04:21    [W:1.549 / U:0.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site