On 02/08/2014 02:24 PM, Linus Torvalds wrote:
> On Sat, Feb 8, 2014 at 12:44 PM, Richard Yao <r...@gentoo.org> wrote:
>>
>> However, is_vmalloc_addr() only applies to the vmalloc region. While all
>> architectures load kernel modules into virtual memory (to my knowledge),
>> some architectures do not load them into the vmalloc region.
>
> So?
>
> People shouldn't do IO to module data, so who cares if something is a
> module address or not?
>
> The thing is, even module *loading* doesn't do IO to the magic module
> addresses - it loads the module data into regular vmalloc space, and
> then copies it into the final location separately.
>
> And no module should ever do any IO on random static data (and
> certainly not on code).
>
> So there is _zero_ reason for a driver or a filesystem to use
> is_vmalloc_or_module_addr(). It's just not a valid question to ask.
>
> If somebody uses module data/code addresses, we're *better* off with a
> oops or other nasty behavior than to try to make it "work".
I agree that reading to module space is awful, but is it obviously
terrible for a module to do this:
static const char header[] = {...};
kernel_write(file, header, sizeof(header), 0);
The current nasty behavior is doing the I/O to the wrong place if the
appropriate CONFIG_DEBUG option isn't set. That IMO sucks.
--Andy
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