linux-kernel - RE: drm/mgag200: doesn't work in panic context

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Date:	Fri, 26 Jun 2015 18:30:32 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Daniel Vetter <daniel.vetter@...ll.ch>,
	"Wang, Rui Y" <rui.y.wang@...el.com>
CC:	Dave Airlie <airlied@...hat.com>,
	"Clark, Rob" <robdclark@...il.com>,
	"Roper, Matthew D" <matthew.d.roper@...el.com>,
	"Chen, Gong" <gong.chen@...el.com>, Borislav Petkov <bp@...en8.de>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: RE: drm/mgag200: doesn't work in panic context

>> I'm here to report two panics which hang forever (the machine cannot reboot). It is because mgag200 doesn't work in panic context. It sleeps and allocates memory non-atomically.
>
> This is the same for all drm drivers, the drm atomic handling with
> fbcon/fbdev is totally broken. It would be serious work to fix this
> properly.

It's a serious problem when a server crashes ... even worse when it hangs while doing so
because we have to rely on some other agent to notice the hung server and go poke it
with a stick.

If it is too hard to fix all of the drivers, is it possible to attack this in the allocator?

-Tony