* [PATCH] mm: bugfix: set current->reclaim_state to NULL while returning from kswapd()
@ 2012-11-05 20:13 Aaditya Kumar
2012-11-05 21:44 ` David Rientjes
0 siblings, 1 reply; 2+ messages in thread
From: Aaditya Kumar @ 2012-11-05 20:13 UTC (permalink / raw)
To: LKML, linux-mm
Cc: kosaki.motohiro, KAMEZAWA Hiroyuki, KOSAKI Motohiro, Mel Gorman,
akpm, Minchan Kim, takamori.yamaguchi, takuzo.ohara,
amit.agarwal, tim.bird, frank.rowand, kan.iibuchi, aaditya.kumar
From: Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com>
In kswapd(), set current->reclaim_state to NULL before returning, as
current->reclaim_state holds reference to variable on kswapd()'s stack.
In rare cases, while returning from kswapd() during memory off lining,
__free_slab() can access dangling pointer of current->reclaim_state.
Signed-off-by: Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com>
Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2624edc..8b055e9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3017,6 +3017,8 @@ static int kswapd(void *p)
&balanced_classzone_idx);
}
}
+
+ current->reclaim_state = NULL;
return 0;
}
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* Re: [PATCH] mm: bugfix: set current->reclaim_state to NULL while returning from kswapd()
2012-11-05 20:13 [PATCH] mm: bugfix: set current->reclaim_state to NULL while returning from kswapd() Aaditya Kumar
@ 2012-11-05 21:44 ` David Rientjes
0 siblings, 0 replies; 2+ messages in thread
From: David Rientjes @ 2012-11-05 21:44 UTC (permalink / raw)
To: Aaditya Kumar
Cc: LKML, linux-mm, kosaki.motohiro, KAMEZAWA Hiroyuki,
KOSAKI Motohiro, Mel Gorman, akpm, Minchan Kim,
takamori.yamaguchi, takuzo.ohara, amit.agarwal, tim.bird,
frank.rowand, kan.iibuchi, aaditya.kumar
On Tue, 6 Nov 2012, Aaditya Kumar wrote:
> From: Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com>
>
> In kswapd(), set current->reclaim_state to NULL before returning, as
> current->reclaim_state holds reference to variable on kswapd()'s stack.
>
> In rare cases, while returning from kswapd() during memory off lining,
> __free_slab() can access dangling pointer of current->reclaim_state.
>
It's __free_slab() for slub and kmem_freepages() for slab.
> Signed-off-by: Takamori Yamaguchi <takamori.yamaguchi@jp.sony.com>
> Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Acked-by: David Rientjes <rientjes@google.com>
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