Hi Tvrtko,

On 8/13/24 07:25, Tvrtko Ursulin wrote:

From: Tvrtko Ursulin tvrtko.ursulin@igalia.com

We forgot to disable preemption around the write_seqcount_begin/end() pair while updating GPU stats:

[ ] WARNING: CPU: 2 PID: 12 at include/linux/seqlock.h:221 __seqprop_assert.isra.0+0x128/0x150 [v3d] [ ] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched] <...snip...> [ ] Call trace: [ ] __seqprop_assert.isra.0+0x128/0x150 [v3d] [ ] v3d_job_start_stats.isra.0+0x90/0x218 [v3d] [ ] v3d_bin_job_run+0x23c/0x388 [v3d] [ ] drm_sched_run_job_work+0x520/0x6d0 [gpu_sched] [ ] process_one_work+0x62c/0xb48 [ ] worker_thread+0x468/0x5b0 [ ] kthread+0x1c4/0x1e0 [ ] ret_from_fork+0x10/0x20

Fix it.

Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@igalia.com Fixes: 6abe93b621ab ("drm/v3d: Fix race-condition between sysfs/fdinfo and interrupt handler") Cc: Maíra Canal mcanal@igalia.com Cc: stable@vger.kernel.org # v6.10+ Acked-by: Maíra Canal mcanal@igalia.com

I just applied this patch to drm-misc-fixes. I'll wait for drm-misc- fixes to be backported to drm-misc-next before applying the second patch to drm-misc-next.

Thanks for your contribution!

Best Regards, - Maíra

---

drivers/gpu/drm/v3d/v3d_sched.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c index 42d4f4a2dba2..cc2e5a89467b 100644 --- a/drivers/gpu/drm/v3d/v3d_sched.c +++ b/drivers/gpu/drm/v3d/v3d_sched.c @@ -136,6 +136,8 @@ v3d_job_start_stats(struct v3d_job *job, enum v3d_queue queue) struct v3d_stats *local_stats = &file->stats[queue]; u64 now = local_clock();

• preempt_disable();
• write_seqcount_begin(&local_stats->lock); local_stats->start_ns = now; write_seqcount_end(&local_stats->lock);

@@ -143,6 +145,8 @@ v3d_job_start_stats(struct v3d_job *job, enum v3d_queue queue) write_seqcount_begin(&global_stats->lock); global_stats->start_ns = now; write_seqcount_end(&global_stats->lock);

• preempt_enable(); }

static void @@ -164,8 +168,10 @@ v3d_job_update_stats(struct v3d_job *job, enum v3d_queue queue) struct v3d_stats *local_stats = &file->stats[queue]; u64 now = local_clock();

• preempt_disable(); v3d_stats_update(local_stats, now); v3d_stats_update(global_stats, now);
• preempt_enable(); }

static struct dma_fence *v3d_bin_job_run(struct drm_sched_job *sched_job)