linux/drivers/gpu
Marek Czernohous 511585987d drm/nouveau: unsubscribe the channel-kill event before the fence context
nouveau_channel_del() tears the fence context down first and only drops
the channel-kill subscription later, in the middle of the nvif object
teardown:

	if (chan->fence)
		nouveau_fence(chan->cli->drm)->context_del(chan);
	...
	nvif_object_dtor(&chan->vram);
	nvif_event_dtor(&chan->kill);

The subscribed handler is nouveau_channel_killed(), which calls
nouveau_channel_kill() and from there nouveau_fence_context_kill() on
chan->fence. A kill event delivered in that window takes fctx->lock and
walks fctx->pending on a fence context that context_del() has already
freed.

Nothing reaches this below Fermi today, because the subscription is
gated on FERMI_CHANNEL_GPFIFO and nothing kills a channel there. On
Fermi and newer the window is real but narrow, since a kill has to land
exactly while the channel is being destroyed. That is reason enough on
its own, which is why this carries a Fixes: tag. The last patch in this
series subscribes Tesla channels as well; nothing kills those today, so
it does not widen the exposure now, but it is the groundwork for a
recovery path that would, and the ordering is better fixed before that
lands than alongside it.

Drop the subscription before anything it depends on is torn down.

Fixes: ea13e5abf8 ("drm/nouveau: signal pending fences when channel has been killed")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: Marek Czernohous <marek@czernohous.de>
Fixes: ea13e5abf8 ("drm/nouveau: signal pending fences when channel has been killed")
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/20260812231330.705425-2-mczernohous@gmail.com
2026-08-20 17:33:43 -04:00
..
drm drm/nouveau: unsubscribe the channel-kill event before the fence context 2026-08-20 17:33:43 -04:00
host1x gpu: host1x: Fix use-after-free in host1x_bo_clear_cached_mappings 2026-07-16 20:26:28 +02:00
ipu-v3
nova-core drm-next for 7.2-rc1 2026-06-17 10:21:00 +01:00
tests
trace
vga fbdev: Wrap fbcon updates from vga-switcheroo in helper 2026-06-09 16:00:11 +02:00
buddy.c gpu/buddy: bail out of try_harder when alignment cannot be honoured 2026-07-09 18:49:49 +05:30
Kconfig
Makefile