From: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Cc: Emily.Deng@amd.com, steven.price@arm.com,
amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
Christian.Koenig@amd.com
Subject: Re: [PATCH v4] drm/scheduler: Avoid accessing freed bad job.
Date: Tue, 26 Nov 2019 10:37:11 -0500 [thread overview]
Message-ID: <b8b716a7-e235-38b2-ea6d-0a21881fa64e@amd.com> (raw)
Message-ID: <20191126153711.ADo4tGqR-RYbzqQc2i6KwXSDYFvI16Ccz5IhKKN7MAo@z> (raw)
In-Reply-To: <1574715089-14875-1-git-send-email-andrey.grodzovsky@amd.com>
Ping
Andrey
On 11/25/19 3:51 PM, Andrey Grodzovsky wrote:
> Problem:
> Due to a race between drm_sched_cleanup_jobs in sched thread and
> drm_sched_job_timedout in timeout work there is a possiblity that
> bad job was already freed while still being accessed from the
> timeout thread.
>
> Fix:
> Instead of just peeking at the bad job in the mirror list
> remove it from the list under lock and then put it back later when
> we are garanteed no race with main sched thread is possible which
> is after the thread is parked.
>
> v2: Lock around processing ring_mirror_list in drm_sched_cleanup_jobs.
>
> v3: Rebase on top of drm-misc-next. v2 is not needed anymore as
> drm_sched_get_cleanup_job already has a lock there.
>
> v4: Fix comments to relfect latest code in drm-misc.
>
> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
> Reviewed-by: Christian König <christian.koenig@amd.com>
> Tested-by: Emily Deng <Emily.Deng@amd.com>
> ---
> drivers/gpu/drm/scheduler/sched_main.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index 6774955..1bf9c40 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -284,10 +284,21 @@ static void drm_sched_job_timedout(struct work_struct *work)
> unsigned long flags;
>
> sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
> +
> + /* Protects against concurrent deletion in drm_sched_get_cleanup_job */
> + spin_lock_irqsave(&sched->job_list_lock, flags);
> job = list_first_entry_or_null(&sched->ring_mirror_list,
> struct drm_sched_job, node);
>
> if (job) {
> + /*
> + * Remove the bad job so it cannot be freed by concurrent
> + * drm_sched_cleanup_jobs. It will be reinserted back after sched->thread
> + * is parked at which point it's safe.
> + */
> + list_del_init(&job->node);
> + spin_unlock_irqrestore(&sched->job_list_lock, flags);
> +
> job->sched->ops->timedout_job(job);
>
> /*
> @@ -298,6 +309,8 @@ static void drm_sched_job_timedout(struct work_struct *work)
> job->sched->ops->free_job(job);
> sched->free_guilty = false;
> }
> + } else {
> + spin_unlock_irqrestore(&sched->job_list_lock, flags);
> }
>
> spin_lock_irqsave(&sched->job_list_lock, flags);
> @@ -370,6 +383,20 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
> kthread_park(sched->thread);
>
> /*
> + * Reinsert back the bad job here - now it's safe as
> + * drm_sched_get_cleanup_job cannot race against us and release the
> + * bad job at this point - we parked (waited for) any in progress
> + * (earlier) cleanups and drm_sched_get_cleanup_job will not be called
> + * now until the scheduler thread is unparked.
> + */
> + if (bad && bad->sched == sched)
> + /*
> + * Add at the head of the queue to reflect it was the earliest
> + * job extracted.
> + */
> + list_add(&bad->node, &sched->ring_mirror_list);
> +
> + /*
> * Iterate the job list from later to earlier one and either deactive
> * their HW callbacks or remove them from mirror list if they already
> * signaled.
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next prev parent reply other threads:[~2019-11-26 15:37 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 20:51 [PATCH v4] drm/scheduler: Avoid accessing freed bad job Andrey Grodzovsky
2019-11-25 20:51 ` Andrey Grodzovsky
2019-11-25 21:44 ` Deng, Emily
2019-11-25 21:44 ` Deng, Emily
2019-11-26 0:09 ` Grodzovsky, Andrey
2019-11-26 0:09 ` Grodzovsky, Andrey
[not found] ` <MWHPR12MB1453C6FC45A83482232CA3EDEA450-Gy0DoCVfaSWZBIDmKHdw+wdYzm3356FpvxpqHgZTriW3zl9H0oFU5g@public.gmane.org>
2019-11-26 15:36 ` Deucher, Alexander
2019-11-26 15:36 ` Deucher, Alexander
2019-11-26 15:37 ` Andrey Grodzovsky [this message]
2019-11-26 15:37 ` Andrey Grodzovsky
[not found] ` <b8b716a7-e235-38b2-ea6d-0a21881fa64e-5C7GfCeVMHo@public.gmane.org>
2019-11-27 0:41 ` Deng, Emily
2019-11-27 0:41 ` Deng, Emily
2019-12-02 19:24 ` Deng, Emily
2019-12-03 19:10 ` Andrey Grodzovsky
2019-12-03 19:44 ` Deucher, Alexander
2019-12-03 19:57 ` Andrey Grodzovsky
2019-12-03 19:59 ` Deucher, Alexander
2019-12-03 20:32 ` Andrey Grodzovsky
2019-12-03 20:58 ` Deng, Emily
2019-12-03 19:53 ` Deng, Emily
2020-02-05 18:24 ` Lucas Stach
2020-02-06 11:10 ` Lucas Stach
2020-02-06 11:49 ` Christian König
2020-02-06 14:49 ` Alex Deucher
2020-02-06 14:51 ` Christian König
2020-02-06 15:49 ` Andrey Grodzovsky
2020-02-10 16:55 ` Andrey Grodzovsky
2020-02-10 21:50 ` Luben Tuikov
2020-02-11 15:55 ` Andrey Grodzovsky
2020-02-11 21:27 ` Andrey Grodzovsky
2020-02-12 0:53 ` Luben Tuikov
2020-02-12 16:33 ` Andrey Grodzovsky
2020-07-21 11:03 ` Lucas Stach
2020-07-21 13:36 ` Andrey Grodzovsky
2020-07-21 13:39 ` Christian König
2020-07-21 13:42 ` Andrey Grodzovsky
2020-07-21 18:29 ` Luben Tuikov
2020-11-25 3:17 ` [PATCH 0/6] Allow to extend the timeout without jobs disappearing Luben Tuikov
2020-11-25 3:17 ` [PATCH 1/6] drm/scheduler: "node" --> "list" Luben Tuikov
2020-11-25 9:44 ` Christian König
2020-11-25 3:17 ` [PATCH 2/6] gpu/drm: ring_mirror_list --> pending_list Luben Tuikov
2020-11-25 9:47 ` Christian König
2020-11-25 16:42 ` Luben Tuikov
2020-11-25 3:17 ` [PATCH 3/6] drm/scheduler: Job timeout handler returns status Luben Tuikov
2020-11-25 4:41 ` kernel test robot
2020-11-25 9:50 ` Christian König
2020-11-25 16:48 ` Luben Tuikov
2020-11-25 11:04 ` Steven Price
2020-11-25 11:15 ` Lucas Stach
2020-11-25 11:22 ` Steven Price
2020-11-25 11:47 ` Lucas Stach
2020-11-25 12:41 ` Christian König
2020-11-26 15:06 ` Andrey Grodzovsky
2020-11-25 3:17 ` [PATCH 4/6] drm/scheduler: Essentialize the job done callback Luben Tuikov
2020-11-25 9:51 ` Christian König
2020-11-25 3:17 ` [PATCH 5/6] drm/amdgpu: Don't hardcode thread name length Luben Tuikov
2020-11-25 9:55 ` Christian König
2020-11-25 17:01 ` Luben Tuikov
2020-11-26 8:11 ` Christian König
2020-11-25 3:17 ` [PATCH 6/6] drm/sched: Make use of a "done" thread Luben Tuikov
2020-11-25 10:10 ` Christian König
2020-11-26 0:24 ` Luben Tuikov
2020-11-25 11:09 ` Steven Price
2020-11-26 0:30 ` Luben Tuikov
2020-02-07 15:26 ` [PATCH v4] drm/scheduler: Avoid accessing freed bad job Daniel Vetter
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