<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style> </head> <body dir="ltr"> [AMD Official Use Only - Internal Distribution Only] <div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> Please go ahead an apply whatever version is necessary for amd-staging-drm-next.</div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> </div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> Alex</div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> </div> <div id="appendonsend"></div> <hr style="display:inline-block;width:98%" tabindex="-1"> <div id="divRplyFwdMsg" dir="ltr">From: Grodzovsky, Andrey <Andrey.Grodzovsky@amd.com> Sent: Tuesday, December 3, 2019 2:10 PM To: Deng, Emily <Emily.Deng@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com> Cc: dri-devel@lists.freedesktop.org <dri-devel@lists.freedesktop.org>; amd-gfx@lists.freedesktop.org <amd-gfx@lists.freedesktop.org>; Koenig, Christian <Christian.Koenig@amd.com>; steven.price@arm.com <steven.price@arm.com> Subject: Re: [PATCH v4] drm/scheduler: Avoid accessing freed bad job. <div> </div> </div> <div class="BodyFragment"> <div class="PlainText">Yes - Christian just pushed it to drm-next-misc - I guess Alex/Christian didn't pull to amd-staging-drm-next yet. Andrey On 12/2/19 2:24 PM, Deng, Emily wrote: > [AMD Official Use Only - Internal Distribution Only] > > Hi Andrey, > Seems this patch is still not in amd-staging-drm-next? > > Best wishes > Emily Deng > > > >> -----Original Message----- >> From: Deng, Emily >> Sent: Tuesday, November 26, 2019 4:41 PM >> To: Grodzovsky, Andrey <Andrey.Grodzovsky@amd.com> >> Cc: dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org; Koenig, >> Christian <Christian.Koenig@amd.com>; steven.price@arm.com >> Subject: RE: [PATCH v4] drm/scheduler: Avoid accessing freed bad job. >> >> [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. </div> </div> </div> </body> </html>