[PATCH] memory hotplug: reset pgdat->kswapd to NULL if creating kernel thread fails

[Wen Congyang <wency@xxxxxxxxxxxxxx>]

If kthread_run() fails, pgdat->kswapd contains errno. When we stop
this thread, we only check whether pgdat->kswapd is NULL and access
it. If it contains errno, it will cause page fault. Reset pgdat->kswapd
to NULL when creating kernel thread fails can avoid this problem.

Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
---
 mm/vmscan.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 347b3ff..1e8e2aa 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2953,6 +2953,7 @@ int kswapd_run(int nid)
 		/* failure at boot is fatal */
 		BUG_ON(system_state == SYSTEM_BOOTING);
 		printk("Failed to start kswapd on node %d\n",nid);
+		pgdat->kswapd = NULL;
 		ret = -1;
 	}
 	return ret;
-- 
1.7.1
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