From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH v2 06/35] nds32: MMU fault handling and page table
 management
Date: Thu, 7 Dec 2017 16:40:41 +0000
Message-ID: <20171207164040.GD21978@ZenIV.linux.org.uk>
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To: Greentime Hu <green.hu@gmail.com>
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On Mon, Nov 27, 2017 at 08:27:53PM +0800, Greentime Hu wrote:
> +void do_page_fault(unsigned long entry, unsigned long addr,
> +		   unsigned int error_code, struct pt_regs *regs)
[snip]
> +	/*
> +	 * If we're in an interrupt or have no user
> +	 * context, we must not take the fault..
> +	 */
> +	if (unlikely(in_atomic() || !mm))

Broken.  in_atomic() is wrong here - it should be faulthandler_disabled().