On Fri, Aug 14, 2026 at 02:57:11PM +0200, not into names wrote:
> hi.
>
> i block everything everywhere all the time all at once. sendbug could
> have a retry so when it can't connect out i can allow the outgoing ips
> and try again, so i don't have to type it a second time, which i won't.
> so here short version:
>
> login: kernel: protection fault trap, code=0
> Stopped at dma_fence_chain_walk+0xba: movq
> 0x18(%rax),%r11
> dbb{0}>
>
> had to press reset. i guess "login:" was still there from boot. i
> was watching some webm i downloaded from the youtubes. nothing special,
> do that all the time. was over sshfs though. also doing that all the
> time.
It is unclear which fence this is without a full trace.
If you can reproduce it, does it still occur with this?
Index: sys/dev/pci/drm/drm_linux.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/drm_linux.c,v
diff -u -p -r1.144 drm_linux.c
--- sys/dev/pci/drm/drm_linux.c 27 Jul 2026 02:24:44 -0000 1.144
+++ sys/dev/pci/drm/drm_linux.c 15 Aug 2026 02:49:18 -0000
@@ -1889,6 +1889,9 @@ dma_fence_is_signaled(struct dma_fence *
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return true;
+ if (fence->ops == NULL)
+ return false;
+
if (fence->ops->signaled && fence->ops->signaled(fence)) {
dma_fence_signal(fence);
return true;
