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

[Mike Travis <travis@sgi.com>]

Ingo Molnar wrote:
> * Yinghai Lu <yinghai@kernel.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