From: Greg Kerr <kerrnel@google.com>
To: Subhra Mazumdar <subhra.mazumdar@oracle.com>
Cc: Aubrey Li <aubrey.intel@gmail.com>,
Mel Gorman <mgorman@techsingularity.net>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Paul Turner <pjt@google.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Fr?d?ric Weisbecker" <fweisbec@gmail.com>,
Kees Cook <keescook@chromium.org>, Greg Kerr <greg@kerrnel.com>
Subject: Re: [RFC][PATCH 00/16] sched: Core scheduling
Date: Mon, 11 Mar 2019 17:20:19 -0700 [thread overview]
Message-ID: <CAJGSLMuLVDXhffOWbnzt8-P7u68OODkN_pwvSt9MBH5mbyAfQQ@mail.gmail.com> (raw)
In-Reply-To: <ac10b8fd-da1a-2cc2-afee-4e2b9b4278ee@oracle.com>
On Mon, Mar 11, 2019 at 4:36 PM Subhra Mazumdar
<subhra.mazumdar@oracle.com> wrote:
>
>
> On 3/11/19 11:34 AM, Subhra Mazumdar wrote:
> >
> > On 3/10/19 9:23 PM, Aubrey Li wrote:
> >> On Sat, Mar 9, 2019 at 3:50 AM Subhra Mazumdar
> >> <subhra.mazumdar@oracle.com> wrote:
> >>> expected. Most of the performance recovery happens in patch 15 which,
> >>> unfortunately, is also the one that introduces the hard lockup.
> >>>
> >> After applied Subhra's patch, the following is triggered by enabling
> >> core sched when a cgroup is
> >> under heavy load.
> >>
> > It seems you are facing some other deadlock where printk is involved.
> > Can you
> > drop the last patch (patch 16 sched: Debug bits...) and try?
> >
> > Thanks,
> > Subhra
> >
> Never Mind, I am seeing the same lockdep deadlock output even w/o patch
> 16. Btw
> the NULL fix had something missing, following works.
Is this panic below, which occurs when I tag the first process,
related or known? If not, I will debug it tomorrow.
[ 46.831828] BUG: unable to handle kernel NULL pointer dereference
at 0000000000000000
[ 46.831829] core sched enabled
[ 46.834261] #PF error: [WRITE]
[ 46.834899] PGD 0 P4D 0
[ 46.835438] Oops: 0002 [#1] SMP PTI
[ 46.836158] CPU: 0 PID: 11 Comm: migration/0 Not tainted
5.0.0everyday-glory-03949-g2d8fdbb66245-dirty #7
[ 46.838206] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.10.2-1 04/01/2014
[ 46.839844] RIP: 0010:_raw_spin_lock+0x7/0x20
[ 46.840448] Code: 00 00 00 65 81 05 25 ca 5c 51 00 02 00 00 31 c0
ba ff 00 00 00 f0 0f b1 17 74 05 e9 93 80 46 ff f3 c3 90 31 c0 ba 01
00 00 00 <f0> 0f b1 17 74 07 89 c6 e9 1c 6e 46 ff f3 c3 66 2e 0f 1f 84
00 00
[ 46.843000] RSP: 0018:ffffb9d300cabe38 EFLAGS: 00010046
[ 46.843744] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004
[ 46.844709] RDX: 0000000000000001 RSI: ffffffffaea435ae RDI: 0000000000000000
[ 46.845689] RBP: ffffb9d300cabed8 R08: 0000000000000000 R09: 0000000000020800
[ 46.846651] R10: ffffffffaf603ea0 R11: 0000000000000001 R12: ffffffffaf6576c0
[ 46.847619] R13: ffff9a57366c8000 R14: ffff9a5737401300 R15: ffffffffade868f0
[ 46.848584] FS: 0000000000000000(0000) GS:ffff9a5737a00000(0000)
knlGS:0000000000000000
[ 46.849680] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 46.850455] CR2: 0000000000000000 CR3: 00000001d36fa000 CR4: 00000000000006f0
[ 46.851415] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 46.852371] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 46.853326] Call Trace:
[ 46.853678] __schedule+0x139/0x11f0
[ 46.854167] ? cpumask_next+0x16/0x20
[ 46.854668] ? cpu_stop_queue_work+0xc0/0xc0
[ 46.855252] ? sort_range+0x20/0x20
[ 46.855742] schedule+0x4e/0x60
[ 46.856171] smpboot_thread_fn+0x12a/0x160
[ 46.856725] kthread+0x112/0x120
[ 46.857164] ? kthread_stop+0xf0/0xf0
[ 46.857661] ret_from_fork+0x35/0x40
[ 46.858146] Modules linked in:
[ 46.858562] CR2: 0000000000000000
[ 46.859022] ---[ end trace e9fff08f17bfd2be ]---
- Greg
>
> --------->8------------
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1d0dac4..27cbc64 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4131,7 +4131,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct
> sched_entity *curr)
> * Avoid running the skip buddy, if running something else can
> * be done without getting too unfair.
> */
> - if (cfs_rq->skip == se) {
> + if (cfs_rq->skip && cfs_rq->skip == se) {
> struct sched_entity *second;
>
> if (se == curr) {
> @@ -4149,13 +4149,15 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct
> sched_entity *curr)
> /*
> * Prefer last buddy, try to return the CPU to a preempted task.
> */
> - if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
> + if (left && cfs_rq->last && wakeup_preempt_entity(cfs_rq->last,
> left)
> + < 1)
> se = cfs_rq->last;
>
> /*
> * Someone really wants this to run. If it's not unfair, run it.
> */
> - 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)
> se = cfs_rq->next;
>
> clear_buddies(cfs_rq, se);
> @@ -6958,6 +6960,9 @@ pick_task_fair(struct rq *rq)
>
> se = pick_next_entity(cfs_rq, NULL);
>
> + if (!(se || curr))
> + return NULL;
> +
> if (curr) {
> if (se && curr->on_rq)
> update_curr(cfs_rq);
>
next prev parent reply other threads:[~2019-03-12 0:20 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 16:56 [RFC][PATCH 00/16] sched: Core scheduling Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 01/16] stop_machine: Fix stop_cpus_in_progress ordering Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 02/16] sched: Fix kerneldoc comment for ia64_set_curr_task Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 03/16] sched: Wrap rq::lock access Peter Zijlstra
2019-02-19 16:13 ` Phil Auld
2019-02-19 16:22 ` Peter Zijlstra
2019-02-19 16:37 ` Phil Auld
2019-03-18 15:41 ` Julien Desfossez
2019-03-20 2:29 ` Subhra Mazumdar
2019-03-21 21:20 ` Julien Desfossez
2019-03-22 13:34 ` Peter Zijlstra
2019-03-22 20:59 ` Julien Desfossez
2019-03-23 0:06 ` Subhra Mazumdar
2019-03-27 1:02 ` Subhra Mazumdar
2019-03-29 13:35 ` Julien Desfossez
2019-03-29 22:23 ` Subhra Mazumdar
2019-04-01 21:35 ` Subhra Mazumdar
2019-04-03 20:16 ` Julien Desfossez
2019-04-05 1:30 ` Subhra Mazumdar
2019-04-02 7:42 ` Peter Zijlstra
2019-03-22 23:28 ` Tim Chen
2019-03-22 23:44 ` Tim Chen
2019-02-18 16:56 ` [RFC][PATCH 04/16] sched/{rt,deadline}: Fix set_next_task vs pick_next_task Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 05/16] sched: Add task_struct pointer to sched_class::set_curr_task Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 06/16] sched/fair: Export newidle_balance() Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 07/16] sched: Allow put_prev_task() to drop rq->lock Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 08/16] sched: Rework pick_next_task() slow-path Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 09/16] sched: Introduce sched_class::pick_task() Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 10/16] sched: Core-wide rq->lock Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 11/16] sched: Basic tracking of matching tasks Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 12/16] sched: A quick and dirty cgroup tagging interface Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 13/16] sched: Add core wide task selection and scheduling Peter Zijlstra
[not found] ` <20190402064612.GA46500@aaronlu>
2019-04-02 8:28 ` Peter Zijlstra
2019-04-02 13:20 ` Aaron Lu
2019-04-05 14:55 ` Aaron Lu
2019-04-09 18:09 ` Tim Chen
2019-04-10 4:36 ` Aaron Lu
2019-04-10 14:18 ` Aubrey Li
2019-04-11 2:11 ` Aaron Lu
2019-04-10 14:44 ` Peter Zijlstra
2019-04-11 3:05 ` Aaron Lu
2019-04-11 9:19 ` Peter Zijlstra
2019-04-10 8:06 ` Peter Zijlstra
2019-04-10 19:58 ` Vineeth Remanan Pillai
2019-04-15 16:59 ` Julien Desfossez
2019-04-16 13:43 ` Aaron Lu
2019-04-09 18:38 ` Julien Desfossez
2019-04-10 15:01 ` Peter Zijlstra
2019-04-11 0:11 ` Subhra Mazumdar
2019-04-19 8:40 ` Ingo Molnar
2019-04-19 23:16 ` Subhra Mazumdar
2019-02-18 16:56 ` [RFC][PATCH 14/16] sched/fair: Add a few assertions Peter Zijlstra
2019-02-18 16:56 ` [RFC][PATCH 15/16] sched: Trivial forced-newidle balancer Peter Zijlstra
2019-02-21 16:19 ` Valentin Schneider
2019-02-21 16:41 ` Peter Zijlstra
2019-02-21 16:47 ` Peter Zijlstra
2019-02-21 18:28 ` Valentin Schneider
2019-04-04 8:31 ` Aubrey Li
2019-04-06 1:36 ` Aubrey Li
2019-02-18 16:56 ` [RFC][PATCH 16/16] sched: Debug bits Peter Zijlstra
2019-02-18 17:49 ` [RFC][PATCH 00/16] sched: Core scheduling Linus Torvalds
2019-02-18 20:40 ` Peter Zijlstra
2019-02-19 0:29 ` Linus Torvalds
2019-02-19 15:15 ` Ingo Molnar
2019-02-22 12:17 ` Paolo Bonzini
2019-02-22 14:20 ` Peter Zijlstra
2019-02-22 19:26 ` Tim Chen
2019-02-26 8:26 ` Aubrey Li
2019-02-27 7:54 ` Aubrey Li
2019-02-21 2:53 ` Subhra Mazumdar
2019-02-21 14:03 ` Peter Zijlstra
2019-02-21 18:44 ` Subhra Mazumdar
2019-02-22 0:34 ` Subhra Mazumdar
2019-02-22 12:45 ` Mel Gorman
2019-02-22 16:10 ` Mel Gorman
2019-03-08 19:44 ` Subhra Mazumdar
2019-03-11 4:23 ` Aubrey Li
2019-03-11 18:34 ` Subhra Mazumdar
2019-03-11 23:33 ` Subhra Mazumdar
2019-03-12 0:20 ` Greg Kerr [this message]
2019-03-12 0:47 ` Subhra Mazumdar
2019-03-12 7:33 ` Aaron Lu
2019-03-12 7:45 ` Aubrey Li
2019-03-13 5:55 ` Aubrey Li
2019-03-14 0:35 ` Tim Chen
2019-03-14 5:30 ` Aubrey Li
2019-03-14 6:07 ` Li, Aubrey
2019-03-18 6:56 ` Aubrey Li
2019-03-12 19:07 ` Pawan Gupta
2019-03-26 7:32 ` Aaron Lu
2019-03-26 7:56 ` Aaron Lu
2019-02-19 22:07 ` Greg Kerr
2019-02-20 9:42 ` Peter Zijlstra
2019-02-20 18:33 ` Greg Kerr
2019-02-22 14:10 ` Peter Zijlstra
2019-03-07 22:06 ` Paolo Bonzini
2019-02-20 18:43 ` Subhra Mazumdar
2019-03-01 2:54 ` Subhra Mazumdar
2019-03-14 15:28 ` Julien Desfossez
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