[+Philip]
On 2018-04-20 10:47 AM, Michel Dänzer wrote:
On 2018-04-11 11:37 AM, Christian König wrote:
Am 11.04.2018 um 06:00 schrieb Gabriel C:
2018-04-09 11:42 GMT+02:00 Christian König ckoenig.leichtzumerken@gmail.com:
Am 07.04.2018 um 00:00 schrieb Jean-Marc Valin:
Hi Christian,
Thanks for the info. FYI, I've also opened a Firefox bug for that at: https://bugzilla.mozilla.org/show_bug.cgi?id=1448778 Feel free to comment since you have a better understanding of what's going on.
One last question: right now I'm running 4.15.0 with the "offending" patch reverted. Is that safe to run or are there possible bad interactions with other changes.
That should work without problems.
But I just had another idea as well, if you want you could still test the new code path which will be using in 4.17.
While Firefox may do some strange things is not about only Firefox.
With your patches my EPYC box is unusable with 4.15++ kernels. The whole Desktop is acting weird. This one is using an Cape Verde PRO [Radeon HD 7750/8740 / R7 250E] GPU.
Box is 2 * EPYC 7281 with 128 GB ECC RAM
Also a 14C Xeon box with a HD7700 is broken same way.
The hardware is irrelevant for this. We need to know what software stack you use on top of it.
E.g. desktop environment/Mesa and DDX version etc...
Everything breaks in X .. scrolling , moving windows , flickering etc.
reverting f4c809914a7c3e4a59cf543da6c2a15d0f75ee38 and 648bc3574716400acc06f99915815f80d9563783 from an 4.15 kernel makes things work again.
Backporting all the detection logic is to invasive, but you could just go into drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c and forcefull use the other code path.
Just look out for "#ifdef CONFIG_SWIOTLB" checks and disable those.
Well you really can't be serious about these suggestions ? Are you ?
Telling peoples to #if 0 random code is not a solution.
That is for testing and not a permanent solution.
You broke existsing working userland with your patches and at least please fix that for 4.16.
I can help testing code for 4.17/++ if you wish but that is *different* storry.
Please test Alex's amd-staging-drm-next branch from git://people.freedesktop.org/~agd5f/linux.
I think we're still missing something here.
I'm currently running 4.16.2 + the DRM subsystem changes which are going into 4.17 (so I have the changes Christian is referring to) with a Kaveri APU, and I'm seeing similar symptoms as described by Jean-Marc. Some observations:
Firefox, Thunderbird, or worst, gnome-shell, can freeze for up to on the order of a minute, during which the kernel is spending most of one core's cycles inside alloc_pages (__alloc_pages_nodemask to be more precise), called from ttm_alloc_new_pages.
Philip debugged a similar problem with a KFD memory stress test about two weeks ago, where the kernel was seemingly stuck in an infinite loop trying to allocate huge pages. I'm pasting his analysis for the record:
[...] it uses huge_flags GFP_TRANSHUGE to call alloc_pages(), this seems a corner case inside __alloc_pages_slowpath(), it never exits but goes to retry path every time. It can reclaim pages and did_some_progress (as a result, no_progress_loops is reset to 0 every loop, never reach MAX_RECLAIM_RETRIES) but cannot finish huge page allocations under this specific memory pressure.
As a workaround to unblock our release branch testing we removed transparent huge page allocation from ttm_get_pages. We're seeing this as far back as 4.13 on our release branch.
If we're really talking about the same problem, I don't think it's caused by recent page allocator changes, but rather exposed by recent TTM changes.
Regards, Felix
At least in the case of Firefox, this happens due to Mesa internal BO allocations for glTex(Sub)Image, so it's not obvious that Firefox is doing something wrong.
I never noticed this before this week. Before, I was running 4.15.y + DRM subsystem changes from 4.16. Maybe something has changed in core code, trying harder to allocate huge pages.
Maybe TTM should only try to use any huge pages that happen to be available, not spend any (/ "too much"?) additional effort trying to free up huge pages?