From: Vineeth Pillai <viremana@linux.microsoft.com>
To: "Li, Aubrey" <aubrey.li@linux.intel.com>,
Joel Fernandes <joel@joelfernandes.org>
Cc: "Nishanth Aravamudan" <naravamudan@digitalocean.com>,
"Julien Desfossez" <jdesfossez@digitalocean.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Tim Chen" <tim.c.chen@linux.intel.com>,
"Aaron Lu" <aaron.lwe@gmail.com>,
"Aubrey Li" <aubrey.intel@gmail.com>,
"Thomas Glexiner" <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
"Ingo Molnar" <mingo@kernel.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Frederic Weisbecker" <fweisbec@gmail.com>,
"Kees Cook" <keescook@chromium.org>,
"Greg Kerr" <kerrnel@google.com>, "Phil Auld" <pauld@redhat.com>,
"Valentin Schneider" <valentin.schneider@arm.com>,
"Mel Gorman" <mgorman@techsingularity.net>,
"Pawan Gupta" <pawan.kumar.gupta@linux.intel.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
vineeth@bitbyteword.org, "Chen Yu" <yu.c.chen@intel.com>,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Agata Gruza" <agata.gruza@intel.com>,
"Antonio Gomez Iglesias" <antonio.gomez.iglesias@intel.com>,
graf@amazon.com, konrad.wilk@oracle.com,
"Dario Faggioli" <dfaggioli@suse.com>,
"Paul Turner" <pjt@google.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Patrick Bellasi" <derkling@google.com>,
"benbjiang(蒋彪)" <benbjiang@tencent.com>,
"Alexandre Chartre" <alexandre.chartre@oracle.com>,
James.Bottomley@hansenpartnership.com, OWeisse@umich.edu,
"Dhaval Giani" <dhaval.giani@oracle.com>,
"Junaid Shahid" <junaids@google.com>,
"Jesse Barnes" <jsbarnes@google.com>,
"Hyser,Chris" <chris.hyser@oracle.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Tim Chen" <tim.c.chen@intel.com>,
"Ning, Hongyu" <hongyu.ning@linux.intel.com>
Subject: Re: [PATCH v8 -tip 02/26] sched: Introduce sched_class::pick_task()
Date: Sat, 24 Oct 2020 07:10:26 -0400 [thread overview]
Message-ID: <4241e5ac-ecdf-8634-fa0d-dd6759e477e1@linux.microsoft.com> (raw)
In-Reply-To: <d9a70e58-f424-3957-9957-b89071480005@linux.intel.com>
Hi Aubrey,
On 10/23/20 10:48 PM, Li, Aubrey wrote:
>
>>>> 2. Do you see the issue in v7? Not much if at all has changed in this
>>>> part of the code from v7 -> v8 but could be something in the newer
>>>> kernel.
>>>>
>>> IIRC, I can run uperf successfully on v7.
>>> I'm on tip/master 2d3e8c9424c9 (origin/master) "Merge branch 'linus'."
>>> Please let me know if this is a problem, or you have a repo I can pull
>>> for testing.
>> Here is a repo with v8 series on top of v5.9 release:
>> https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git/log/?h=coresched-v5.9
> I didn't see NULL pointer dereference BUG of this repo, will post performance
> data later.
There has been a change in tip in pick_next_entity which caused
removal of a coresched related change to fix the crash. Could
you please try this patch on top of the posted v8 and see if this
works?
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 93a3b874077d..4cae5ac48b60 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4428,12 +4428,14 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
se = second;
}
- if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) {
+ if (left && cfs_rq->next &&
+ wakeup_preempt_entity(cfs_rq->next, left) < 1) {
/*
* Someone really wants this to run. If it's not unfair, run it.
*/
se = cfs_rq->next;
- } else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) {
+ } else if (left && cfs_rq->last &&
+ wakeup_preempt_entity(cfs_rq->last, left) < 1) {
/*
* Prefer last buddy, try to return the CPU to a preempted task.
There reason for left being NULL needs to be investigated. This was
there from v1 and we did not yet get to it. I shall try to debug later
this week.
Kindly test this patch and let us know if it fixes the crash.
Thanks,
Vineeth
next prev parent reply other threads:[~2020-10-24 11:11 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 1:43 [PATCH v8 -tip 00/26] Core scheduling Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 01/26] sched: Wrap rq::lock access Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 02/26] sched: Introduce sched_class::pick_task() Joel Fernandes (Google)
2020-10-22 7:59 ` Li, Aubrey
2020-10-22 15:25 ` Joel Fernandes
2020-10-23 5:25 ` Li, Aubrey
2020-10-23 21:47 ` Joel Fernandes
2020-10-24 2:48 ` Li, Aubrey
2020-10-24 11:10 ` Vineeth Pillai [this message]
2020-10-24 12:27 ` Vineeth Pillai
2020-10-24 23:48 ` Li, Aubrey
2020-10-26 9:01 ` Peter Zijlstra
2020-10-27 3:17 ` Li, Aubrey
2020-10-27 14:19 ` Joel Fernandes
2020-10-27 15:23 ` Joel Fernandes
2020-10-27 14:14 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 03/26] sched: Core-wide rq->lock Joel Fernandes (Google)
2020-10-26 11:59 ` Peter Zijlstra
2020-10-27 16:27 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 04/26] sched/fair: Add a few assertions Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 05/26] sched: Basic tracking of matching tasks Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 06/26] sched: Add core wide task selection and scheduling Joel Fernandes (Google)
2020-10-23 13:51 ` Peter Zijlstra
2020-10-23 13:54 ` Peter Zijlstra
2020-10-23 17:57 ` Joel Fernandes
2020-10-23 19:26 ` Peter Zijlstra
2020-10-23 21:31 ` Joel Fernandes
2020-10-26 8:28 ` Peter Zijlstra
2020-10-27 16:58 ` Joel Fernandes
2020-10-26 9:31 ` Peter Zijlstra
2020-11-05 18:50 ` Joel Fernandes
2020-11-05 22:07 ` Joel Fernandes
2020-10-23 15:05 ` Peter Zijlstra
2020-10-23 17:59 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 07/26] sched/fair: Fix forced idle sibling starvation corner case Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 08/26] sched/fair: Snapshot the min_vruntime of CPUs on force idle Joel Fernandes (Google)
2020-10-26 12:47 ` Peter Zijlstra
2020-10-28 15:29 ` Joel Fernandes
2020-10-28 18:39 ` Joel Fernandes
2020-10-29 16:59 ` Joel Fernandes
2020-10-29 18:24 ` Joel Fernandes
2020-10-29 18:59 ` Peter Zijlstra
2020-10-30 2:36 ` Joel Fernandes
2020-10-30 2:42 ` Joel Fernandes
2020-10-30 8:41 ` Peter Zijlstra
2020-10-31 21:41 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 09/26] sched: Trivial forced-newidle balancer Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 10/26] sched: migration changes for core scheduling Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 11/26] irq_work: Cleanup Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 12/26] arch/x86: Add a new TIF flag for untrusted tasks Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 13/26] kernel/entry: Add support for core-wide protection of kernel-mode Joel Fernandes (Google)
2020-10-20 3:41 ` Randy Dunlap
2020-11-03 0:20 ` Joel Fernandes
2020-10-22 5:48 ` Li, Aubrey
2020-11-03 0:50 ` Joel Fernandes
2020-10-30 10:29 ` Alexandre Chartre
2020-11-03 1:20 ` Joel Fernandes
2020-11-06 16:57 ` Alexandre Chartre
2020-11-06 17:43 ` Joel Fernandes
2020-11-06 18:07 ` Alexandre Chartre
2020-11-10 9:35 ` Alexandre Chartre
2020-11-10 22:42 ` Joel Fernandes
2020-11-16 10:08 ` Alexandre Chartre
2020-11-16 14:50 ` Joel Fernandes
2020-11-16 15:43 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 14/26] entry/idle: Enter and exit kernel protection during idle entry and exit Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 15/26] entry/kvm: Protect the kernel when entering from guest Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 16/26] sched: cgroup tagging interface for core scheduling Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 17/26] sched: Split the cookie and setup per-task cookie on fork Joel Fernandes (Google)
2020-11-04 22:30 ` chris hyser
2020-11-05 14:49 ` Joel Fernandes
2020-11-09 23:30 ` chris hyser
2020-10-20 1:43 ` [PATCH v8 -tip 18/26] sched: Add a per-thread core scheduling interface Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 19/26] sched: Add a second-level tag for nested CGroup usecase Joel Fernandes (Google)
2020-10-31 0:42 ` Josh Don
2020-11-03 2:54 ` Joel Fernandes
[not found] ` <6c07e70d-52f2-69ff-e1fa-690cd2c97f3d@linux.intel.com>
2020-11-05 15:52 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 20/26] sched: Release references to the per-task cookie on exit Joel Fernandes (Google)
2020-11-04 21:50 ` chris hyser
2020-11-05 15:46 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 21/26] sched: Handle task addition to CGroup Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 22/26] sched/debug: Add CGroup node for printing group cookie if SCHED_DEBUG Joel Fernandes (Google)
2020-10-20 1:43 ` [PATCH v8 -tip 23/26] kselftest: Add tests for core-sched interface Joel Fernandes (Google)
2020-10-30 22:20 ` [PATCH] sched: Change all 4 space tabs to actual tabs John B. Wyatt IV
2020-10-20 1:43 ` [PATCH v8 -tip 24/26] sched: Move core-scheduler interfacing code to a new file Joel Fernandes (Google)
2020-10-26 1:05 ` Li, Aubrey
2020-11-03 2:58 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 25/26] Documentation: Add core scheduling documentation Joel Fernandes (Google)
2020-10-20 3:36 ` Randy Dunlap
2020-11-12 16:11 ` Joel Fernandes
2020-10-20 1:43 ` [PATCH v8 -tip 26/26] sched: Debug bits Joel Fernandes (Google)
2020-10-30 13:26 ` [PATCH v8 -tip 00/26] Core scheduling Ning, Hongyu
2020-11-06 2:58 ` Li, Aubrey
2020-11-06 17:54 ` Joel Fernandes
2020-11-09 6:04 ` Li, Aubrey
2020-11-06 20:55 ` [RFT for v9] (Was Re: [PATCH v8 -tip 00/26] Core scheduling) Joel Fernandes
2020-11-13 9:22 ` Ning, Hongyu
2020-11-13 10:01 ` Ning, Hongyu
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