Can you please use addr2line or gdb to pinpoint where in drm_sched_increase_karma you hit the NULL ptr ? It looks like the guilty job, but to be sure. Andrey On 9/27/19 4:12 AM, Neil Armstrong wrote: > Hi Christian, > > In v5.3, running dEQP triggers the following kernel crash : > > [ 20.224982] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038 > [...] > [ 20.291064] Hardware name: Khadas VIM2 (DT) > [ 20.295217] Workqueue: events drm_sched_job_timedout > [...] > [ 20.304867] pc : drm_sched_increase_karma+0x5c/0xf0 > [ 20.309696] lr : drm_sched_increase_karma+0x44/0xf0 > [...] > [ 20.396720] Call trace: > [ 20.399138] drm_sched_increase_karma+0x5c/0xf0 > [ 20.403623] panfrost_job_timedout+0x12c/0x1e0 > [ 20.408021] drm_sched_job_timedout+0x48/0xa0 > [ 20.412336] process_one_work+0x1e0/0x320 > [ 20.416300] worker_thread+0x40/0x450 > [ 20.419924] kthread+0x124/0x128 > [ 20.423116] ret_from_fork+0x10/0x18 > [ 20.426653] Code: f9400001 540001c0 f9400a83 f9402402 (f9401c64) > [ 20.432690] ---[ end trace bd02f890139096a7 ]--- > > Which never happens, at all, on v5.2. > > I did a (very) long (7 days, ~100runs) bisect run using our LAVA lab (thanks tomeu !), but > bisecting was not easy since the bad commit landed on drm-misc-next after v5.1-rc6, and > then v5.2-rc1 was backmerged into drm-misc-next at: > [1] 374ed5429346 Merge drm/drm-next into drm-misc-next > > Thus bisecting between [1] ang v5.2-rc1 leads to commit based on v5.2-rc1... where panfrost was > not enabled in the Khadas VIM2 DT. > > Anyway, I managed to identify 3 possibly breaking commits : > [2] 290764af7e36 drm/sched: Keep s_fence->parent pointer > [3] 5918045c4ed4 drm/scheduler: rework job destruction > [4] a5343b8a2ca5 drm/scheduler: Add flag to hint the release of guilty job. > > But [1] and [2] doesn't crash the same way : > [ 16.257912] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000060 > [...] > [ 16.308307] CPU: 4 PID: 80 Comm: kworker/4:1 Not tainted 5.1.0-rc2-01185-g290764af7e36-dirty #378 > [ 16.317099] Hardware name: Khadas VIM2 (DT) > [...]) > [ 16.330907] pc : refcount_sub_and_test_checked+0x4/0xb0 > [ 16.336078] lr : refcount_dec_and_test_checked+0x14/0x20 > [...] > [ 16.423533] Process kworker/4:1 (pid: 80, stack limit = 0x(____ptrval____)) > [ 16.430431] Call trace: > [ 16.432851] refcount_sub_and_test_checked+0x4/0xb0 > [ 16.437681] drm_sched_job_cleanup+0x24/0x58 > [ 16.441908] panfrost_job_free+0x14/0x28 > [ 16.445787] drm_sched_job_timedout+0x6c/0xa0 > [ 16.450102] process_one_work+0x1e0/0x320 > [ 16.454067] worker_thread+0x40/0x450 > [ 16.457690] kthread+0x124/0x128 > [ 16.460882] ret_from_fork+0x10/0x18 > [ 16.464421] Code: 52800000 d65f03c0 d503201f aa0103e3 (b9400021) > [ 16.470456] ---[ end trace 39a67412ee1b64b5 ]--- > > and [3] fails like on v5.3 (in drm_sched_increase_karma): > [ 33.830080] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038 > [...] > [ 33.871946] Internal error: Oops: 96000004 [#1] PREEMPT SMP > [ 33.877450] Modules linked in: > [ 33.880474] CPU: 6 PID: 81 Comm: kworker/6:1 Not tainted 5.1.0-rc2-01186-ga5343b8a2ca5-dirty #380 > [ 33.889265] Hardware name: Khadas VIM2 (DT) > [ 33.893419] Workqueue: events drm_sched_job_timedout > [...] > [ 33.903069] pc : drm_sched_increase_karma+0x5c/0xf0 > [ 33.907898] lr : drm_sched_increase_karma+0x44/0xf0 > [...] > [ 33.994924] Process kworker/6:1 (pid: 81, stack limit = 0x(____ptrval____)) > [ 34.001822] Call trace: > [ 34.004242] drm_sched_increase_karma+0x5c/0xf0 > [ 34.008726] panfrost_job_timedout+0x12c/0x1e0 > [ 34.013122] drm_sched_job_timedout+0x48/0xa0 > [ 34.017438] process_one_work+0x1e0/0x320 > [ 34.021402] worker_thread+0x40/0x450 > [ 34.025026] kthread+0x124/0x128 > [ 34.028218] ret_from_fork+0x10/0x18 > [ 34.031755] Code: f9400001 540001c0 f9400a83 f9402402 (f9401c64) > [ 34.037792] ---[ end trace be3fd6f77f4df267 ]--- > > > When I revert [3] on [1], i get the same crash as [2], meaning > the commit [3] masks the failure [2] introduced. > > Do you know how to solve this ? > > Thanks, > Neil _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
