On Wed, Nov 19, 2014 at 12:10 AM, Maarten Lankhorst <maarten.lankhorst at canonical.com> 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. > > http://cgit.freedesktop.org/~mlankhorst/linux/commit/?h=fixed-fences-for-bisect&id=86be4f216bbb9ea3339843a5658d4c21162c7ee2
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. > > 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 :) -- Michael Marineau
