Re: sendbug retry - also kernel: protection fault trap

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;