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Date: Tue, 24 May 2011 12:34:33 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Richard Weinberger <richard@nod.at>
Cc: user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
        Joe Perches <joe@perches.com>
Subject: Re: [PATCH 5/7] um: print info about fatal segfaults
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On Sun, 22 May 2011 16:48:34 +0200
Richard Weinberger <richard@nod.at> wrote:

> +static void show_segv_info(struct uml_pt_regs *regs)
> +{
> +	struct task_struct *tsk = current;
> +	struct faultinfo *fi = UPT_FAULTINFO(regs);
> +
> +	if (!unhandled_signal(tsk, SIGSEGV))
> +		return;
> +
> +	if (!printk_ratelimit())
> +		return;
> +
> +	printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
> +		task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
> +		tsk->comm, task_pid_nr(tsk), FAULT_ADDRESS(*fi),
> +		(void *)UPT_IP(regs), (void *)UPT_SP(regs),
> +		fi->error_code);
> +
> +	print_vma_addr(KERN_CONT " in ", UPT_IP(regs));
> +	printk(KERN_CONT "\n");
> +}

Please see the nice comment in printk.h

/*
 * Please don't use printk_ratelimit(), because it shares ratelimiting state
 * with all other unrelated printk_ratelimit() callsites.  Instead use
 * printk_ratelimited() or plain old __ratelimit().
 */

I thought we had a checkpatch rule for this but apparently I dreamed
it.