On Nov 20, 2014 12:53 AM, "Maarten Lankhorst" <<a href="mailto:maarten.lankhorst@canonical.com">maarten.lankhorst@canonical.com</a>> wrote: > > Op 20-11-14 om 05:06 schreef Michael Marineau: > > On Wed, Nov 19, 2014 at 12:10 AM, Maarten Lankhorst > > <<a href="mailto:maarten.lankhorst@canonical.com">maarten.lankhorst@canonical.com</a>> wrote: > >> Hey, > >> > >> On 19-11-14 07:43, Michael Marineau wrote: > >>> On 3.18-rc kernel's I have been intermittently experiencing GPU > >>> lockups shortly after startup, accompanied with one or both of the > >>> following errors: > >>> > >>> nouveau E[ PFIFO][0000:01:00.0] read fault at 0x000734a000 [PTE] > >>> from PBDMA0/HOST_CPU on channel 0x007faa3000 [unknown] > >>> nouveau E[ DRM] GPU lockup - switching to software fbcon > >>> > >>> I was able to trace the issue with bisect to commit > >>> 809e9447b92ffe1346b2d6ec390e212d5307f61c "drm/nouveau: use shared > >>> fences for readable objects". The lockups appear to have cleared up > >>> since reverting that and a few related followup commits: > >>> > >>> 809e9447: "drm/nouveau: use shared fences for readable objects" > >>> 055dffdf: "drm/nouveau: bump driver patchlevel to 1.2.1" > >>> e3be4c23: "drm/nouveau: specify if interruptible wait is desired in > >>> nouveau_fence_sync" > >>> 15a996bb: "drm/nouveau: assign fence_chan->name correctly" > >> Weird. I'm not sure yet what causes it. > >> > >> <a href="http://cgit.freedesktop.org/~mlankhorst/linux/commit/?h=fixed-fences-for-bisect&id=86be4f216bbb9ea3339843a5658d4c21162c7ee2">http://cgit.freedesktop.org/~mlankhorst/linux/commit/?h=fixed-fences-for-bisect&id=86be4f216bbb9ea3339843a5658d4c21162c7ee2</a> > > Building a kernel from that commit gives me an entirely new behavior: > > X hangs for at least 10-20 seconds at a time with brief moments of > > responsiveness before hanging again while gitk on the kernel repo > > loads. Otherwise the system is responsive. The head of that > > fixed-fences-for-bisect branch (1c6aafb5) which is the "use shared > > fences for readable objects" commit I originally bisected to does > > feature the complete lockups I was seeing before. > Ok for the sake of argument lets just assume they're separate bugs, and we should look at xorg > hanging first. > > Is there anything in the dmesg when the hanging happens? Nothing in dmesg, I will try some more experiments shortly including the ones you suggest below. Just in case it wasn't clear those xorg hangs do not happen on the branch head if I get lucky and manage to log in without the GPU lockup so if they are different bugs it at least appears that both present at the same time. > > And it's probably 15 seconds, if it's called through nouveau_fence_wait. > > Try changing else if (!ret) to else if (WARN_ON(!ret)) in that function, and see if you get some dmesg spam. :) > > > >> On the EDITED patch from fixed-fences-for-bisect, can you do the following: > >> > >> In nouveau/nv84_fence.c function nv84_fence_context_new, remove > >> > >> fctx->base.sequence = nv84_fence_read(chan); > >> > >> and add back > >> > >> nouveau_bo_wr32(priv->bo, chan->chid * 16/4, 0x00000000); > > Making your suggested change on top of each 86be4f21 and 1c6aafb5 made > > no noticeable difference in either of the two behaviors. > > > >> If that fails you should compile your kernel with trace events, to get some debugging info from the fences. I'll post debugging info if this does not fix it. > > Happy to gather whatever debug log or tracing data you need :) > > >