On 2018年11月12日 18:48, Chris Wilson wrote:
Quoting Christian König (2018-11-12 10:16:01)Am 09.11.18 um 23:26 schrieb Eric Anholt: Eric Anholt <eric@xxxxxxxxxx> writes: [ Unknown signature status ] zhoucm1 <zhoucm1@xxxxxxx> writes: On 2018年11月09日 00:52, Christian König wrote: Am 08.11.18 um 17:07 schrieb Koenig, Christian: Am 08.11.18 um 17:04 schrieb Eric Anholt: Daniel suggested I submit this, since we're still seeing regressions from it. This is a revert to before 48197bc564c7 ("drm: add syncobj timeline support v9") and its followon fixes. This is a harmless false positive from lockdep, Chouming and I are already working on a fix. On the other hand we had enough trouble with that patch, so if it really bothers you feel free to add my Acked-by: Christian König <christian.koenig@xxxxxxx> and push it. NAK, please no, I don't think this needed, the Warning totally isn't related to syncobj timeline, but fence-array implementation flaw, just exposed by syncobj. In addition, Christian already has a fix for this Warning, I've tested. Please Christian send to public review. I backed out my revert of #2 (#1 still necessary) after adding the lockdep regression fix, and now my CTS run got oomkilled after just a few hours, with these notable lines in the unreclaimable slab info list: [ 6314.373099] drm_sched_fence 69095KB 69095KB [ 6314.373653] kmemleak_object 428249KB 428384KB [ 6314.373736] kmalloc-262144 256KB 256KB [ 6314.373743] kmalloc-131072 128KB 128KB [ 6314.373750] kmalloc-65536 64KB 64KB [ 6314.373756] kmalloc-32768 1472KB 1728KB [ 6314.373763] kmalloc-16384 64KB 64KB [ 6314.373770] kmalloc-8192 208KB 208KB [ 6314.373778] kmalloc-4096 2408KB 2408KB [ 6314.373784] kmalloc-2048 288KB 336KB [ 6314.373792] kmalloc-1024 1457KB 1512KB [ 6314.373800] kmalloc-512 854KB 1048KB [ 6314.373808] kmalloc-256 188KB 268KB [ 6314.373817] kmalloc-192 69141KB 69142KB [ 6314.373824] kmalloc-64 47703KB 47704KB [ 6314.373886] kmalloc-128 46396KB 46396KB [ 6314.373894] kmem_cache 31KB 35KB No results from kmemleak, though. OK, it looks like the #2 revert probably isn't related to the OOM issue. Running a single job on otherwise unused DRM, watching /proc/slabinfo every second for drm_sched_fence, I get: drm_sched_fence 0 0 192 21 1 : tunables 32 16 8 : slabdata 0 0 0 : globalstat 0 0 0 0 0 0 0 0 0 : cpustat 0 0 0 0 drm_sched_fence 16 21 192 21 1 : tunables 32 16 8 : slabdata 1 1 0 : globalstat 16 16 1 0 0 0 0 0 0 : cpustat 5 1 6 0 drm_sched_fence 13 21 192 21 1 : tunables 32 16 8 : slabdata 1 1 0 : globalstat 16 16 1 0 0 0 0 0 0 : cpustat 5 1 6 0 drm_sched_fence 6 21 192 21 1 : tunables 32 16 8 : slabdata 1 1 0 : globalstat 16 16 1 0 0 0 0 0 0 : cpustat 5 1 6 0 drm_sched_fence 4 21 192 21 1 : tunables 32 16 8 : slabdata 1 1 0 : globalstat 16 16 1 0 0 0 0 0 0 : cpustat 5 1 6 0 drm_sched_fence 2 21 192 21 1 : tunables 32 16 8 : slabdata 1 1 0 : globalstat 16 16 1 0 0 0 0 0 0 : cpustat 5 1 6 0 drm_sched_fence 0 21 192 21 1 : tunables 32 16 8 : slabdata 0 1 0 : globalstat 16 16 1 0 0 0 0 0 0 : cpustat 5 1 6 0 So we generate a ton of fences, and I guess free them slowly because of RCU? And presumably kmemleak was sucking up lots of memory because of how many of these objects were laying around. That is certainly possible. Another possibility is that we don't drop the reference in dma-fence-array early enough. E.g. the dma-fence-array will keep the reference to its fences until it is destroyed, which is a bit late when you chain multiple dma-fence-array objects together. David can you take a look at this and propose a fix? That would probably be good to have fixed in dma-fence-array separately to the timeline work.Note that drm_syncobj_replace_fence() leaks any existing fence for !timeline syncobjs.
Hi Chris, Hui! Isn't existing fence collected as garbage? Could you point where/how leaks existing fence? Thanks, David
Which coupled with the linear search ends up with a severe regression in both time and memory. -Chris
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