Re: [RFC PATCH] drm: gpu: msm: forbid mem reclaim from reset

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (26/03/27 05:47), Akhil P Oommen wrote:
> On 3/26/2026 7:24 AM, Sergey Senozhatsky wrote:
> > On (26/01/27 16:33), Sergey Senozhatsky wrote:
> >> We sometimes get into a situtation where GPU hangcheck fails to
> >> recover GPU:
> >>
> >> [..]
> >> msm_dpu ae01000.display-controller: [drm:hangcheck_handler] *ERROR* (IPv4: 1): hangcheck detected gpu lockup rb 0!
> >> msm_dpu ae01000.display-controller: [drm:hangcheck_handler] *ERROR* (IPv4: 1): completed fence: 7840161
> >> msm_dpu ae01000.display-controller: [drm:hangcheck_handler] *ERROR* (IPv4: 1): submitted fence: 7840162
> >> msm_dpu ae01000.display-controller: [drm:hangcheck_handler] *ERROR* (IPv4: 1): hangcheck detected gpu lockup rb 0!
> >> msm_dpu ae01000.display-controller: [drm:hangcheck_handler] *ERROR* (IPv4: 1): completed fence: 7840162
> >> msm_dpu ae01000.display-controller: [drm:hangcheck_handler] *ERROR* (IPv4: 1): submitted fence: 7840163
> >> [..]
> >>
> >> The problem is that msm_job worker is blocked on gpu->lock
> >>
> >> INFO: task ring0:155 blocked for more than 122 seconds.
> >> Not tainted 6.6.99-08727-gaac38b365d2c #1
> >> task:ring0 state:D stack:0 pid:155 ppid:2 flags:0x00000008
> >> Call trace:
> >> __switch_to+0x108/0x208
> >> schedule+0x544/0x11f0
> >> schedule_preempt_disabled+0x30/0x50
> >> __mutex_lock_common+0x410/0x850
> >> __mutex_lock_slowpath+0x28/0x40
> >> mutex_lock+0x5c/0x90
> >> msm_job_run+0x9c/0x140
> >> drm_sched_main+0x514/0x938
> >> kthread+0x114/0x138
> >> ret_from_fork+0x10/0x20
> >>
> >> which is owned by recover worker, which is waiting for DMA fences
> >> from a memory reclaim path, under the very same gpu->lock
> 
> I am still thinking if there is a better way to handle this. Btw, Rob
> had a few fixes related to this area recently. Do you think those would
> help in this scenario?

If you can point me to those fixes then I can take a look.