linux-kernel - Re: [PATCH v4] x86/mce: Avoid infinite loop for copy from user recovery

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Message-ID: <20210115232346.GA7967@agluck-desk2.amr.corp.intel.com>
Date:   Fri, 15 Jan 2021 15:23:46 -0800
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v4] x86/mce: Avoid infinite loop for copy from user
 recovery

On Fri, Jan 15, 2021 at 12:51:03PM -0800, Luck, Tony wrote:
>  static void kill_me_now(struct callback_head *ch)
>  {
> +	p->mce_count = 0;
>  	force_sig(SIGBUS);
>  }

Brown paper bag time ... I just pasted that line from kill_me_maybe()
and I thought I did a re-compile ... but obviously not since it gives

error: ‘p’ undeclared (first use in this function)

Option a) (just like kill_me_maybe)

struct task_struct *p = container_of(cb, struct task_struct, mce_kill_me);

Option b) (simpler ... not sure why PeterZ did the container_of thing

	current->mce_count = 0;

-Tony