[PATCH] mm: bugfix: set current->reclaim_state to NULL whilereturning from kswapd()

[Aaditya Kumar]

From: Takamori Yamaguchi <takamori.yamaguchi@xxxxxxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>

---
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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