On Fri, Dec 20, 2013 at 4:49 PM, Sebastian Andrzej Siewior
<bigeasy@xxxxxxxxxxxxx> wrote:
> On 12/20/2013 04:31 PM, Sebastian Andrzej Siewior wrote:
>> On 12/20/2013 04:27 PM, Geert Uytterhoeven wrote:
>>> On Fri, Dec 20, 2013 at 3:24 PM, Sebastian Andrzej Siewior
>>> <bigeasy@xxxxxxxxxxxxx> wrote:
>>>> If the primary GPU driver has been loaded _after_ system as a module
>>>> then this logo memory is no longer valid.
>>>> Managed to crash the system by booting a box without a GPU and then
>>>> hotpluggin => BOOM.
>>>
>>> drivers/video/fbmem.c:fb_prepare_logo() has protection against this:
>>>
>>> if (info->flags & FBINFO_MISC_TILEBLITTING ||
>>> info->flags & FBINFO_MODULE)
>>> return 0;
>>
>> but gpu driver is built-in. I just add PCI device at run-time. The same
>> thing should happen if you go to sysfs and remove the PCI device and
>> then do
>
> No I see where you are going with this. My description of the problem
> is wrong. The problem is nothing to do with the driver being a module.
Yes, I got confused by the "as a module".
> If nobody objects this or suggests a different solution then I'm going
> to provide a patch with a proper description.
Is "system_state != SYSTEM_BOOTING" the right check?
How long is is in the SYSTEM_BOOTING state?
Ah, kernel_init() does:
free_initmem();
mark_rodata_ro();
system_state = SYSTEM_RUNNING;
So this looks OK to me.
We used to have an initmem_freed flag, but it was removed 15 years
ago. 11 years ago, we got system_state, for the same purpose ;-)
Looking at commit 70802c60379fb843c485dfd4cab9e8f527d8fe81
Author: Antonino A. Daplas <adaplas@xxxxxxxxx>
Date: Tue May 8 00:38:14 2007 -0700
fbdev: don't show logo if driver or fbcon are modular
it seems we were not aware of the existence of system_state....
I guess you can remove FBINFO_MODULE after your fix?
BTW, I'm wondering if modprobing newport_con.ko crashes, too, as
it seems to call fb_find_logo() without any protection.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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