linux-kernel - Re: [PATCH 1/4] printk: Allocate kernel log buffer earlier

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Message-ID: <4D6BF77E.2030107@sgi.com>
Date:	Mon, 28 Feb 2011 11:29:02 -0800
From:	Mike Travis <travis@....com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Yinghai Lu <yinghai@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Jack Steiner <steiner@....com>, Robin Holt <holt@....com>,
	Len Brown <len.brown@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Yinghai Lu <yhlu.kernel@...il.com>, linux-acpi@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 1/4] printk: Allocate kernel log buffer earlier



Ingo Molnar wrote:
> * Yinghai Lu <yinghai@...nel.org> wrote:
> 
>> +	new_addr = memblock_alloc(new_log_buf_len, PAGE_SIZE);
>> +	if (new_addr != MEMBLOCK_ERROR)
>> +		new_log_buf = __va(new_addr);
>> +	else
>> +		new_log_buf = alloc_bootmem(new_log_buf_len);
> 
> alloc_bootmem() can fail, especially if someone uses a too large boot parameter 
> value - and your code does not check for failure.

alloc_bootmem does panic when it can't allocate memory.

Ingo, we have a "uvconfig" script that sets up the boot parameters (there
are many that are needed to be very specific).  It sets up the log_buf_len
to be 8M.  We will never overflow memory with that.

And if someone is stupid enough to try and allocate a log buffer that
consumes more memory than they have, then they have a different kind of
problem.

> 
> Thanks,
> 
> 	Ingo
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