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

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Date:	Tue, 21 Aug 2012 16:37:38 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Wen Congyang <wency@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, mgorman@...e.de,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	hughd@...gle.com, linux-mm@...ck.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] memory hotplug: reset pgdat->kswapd to NULL if creating
 kernel thread fails

On Tue, Aug 21, 2012 at 02:31:19PM +0800, Wen Congyang wrote:
> 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@...fujitsu.com>
Reviewed-by: Minchan Kim <minchan@...nel.org>

Nitpick: Why doesn't online_pages check kswapd_run's return value?
         I hope memory-hotplug can handle this error rightly without
         relying on this patch in the future.

-- 
Kind regards,
Minchan Kim
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