From: "Deng, Emily" <Emily.Deng@amd.com>
To: "Grodzovsky, Andrey" <Andrey.Grodzovsky@amd.com>
Cc: "steven.price@arm.com" <steven.price@arm.com>,
"amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"Koenig, Christian" <Christian.Koenig@amd.com>
Subject: RE: [PATCH v4] drm/scheduler: Avoid accessing freed bad job.
Date: Wed, 27 Nov 2019 00:41:14 +0000 [thread overview]
Message-ID: <MN2PR12MB2975CA8858F21FDF325C33FE8F440@MN2PR12MB2975.namprd12.prod.outlook.com> (raw)
Message-ID: <20191127004114.yvWfJb8pKipsi4JecS52_amvMOvg-bh2c66VIpPctgs@z> (raw)
In-Reply-To: <b8b716a7-e235-38b2-ea6d-0a21881fa64e@amd.com>
[AMD Official Use Only - Internal Distribution Only]
Reviewed-by: Emily Deng <Emily.Deng@amd.com>
>-----Original Message-----
>From: Grodzovsky, Andrey <Andrey.Grodzovsky@amd.com>
>Sent: Tuesday, November 26, 2019 7:37 AM
>Cc: dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org; Koenig,
>Christian <Christian.Koenig@amd.com>; Deng, Emily
><Emily.Deng@amd.com>; steven.price@arm.com
>Subject: Re: [PATCH v4] drm/scheduler: Avoid accessing freed bad job.
>
>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:[~2019-11-27 0:41 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
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 [this message]
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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