From: Juri Lelli <juri.lelli@redhat.com>
To: Quentin Perret <qperret@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] sched: Don't report SCHED_FLAG_SUGOV in sched_getattr()
Date: Wed, 28 Jul 2021 14:36:48 +0200 [thread overview]
Message-ID: <YQFPYIqJG5PSPH1S@localhost.localdomain> (raw)
In-Reply-To: <YQEl2t2RgaB9eEOZ@google.com>
On 28/07/21 10:39, Quentin Perret wrote:
> On Wednesday 28 Jul 2021 at 11:12:03 (+0200), Juri Lelli wrote:
> > Hi Quentin,
> >
> > On 27/07/21 11:11, Quentin Perret wrote:
> > > SCHED_FLAG_SUGOV is supposed to be a kernel-only flag that userspace
> > > cannot interact with. However, sched_getattr() currently reports it
> > > in sched_flags if called on a sugov worker even though it is not
> > > actually defined in a UAPI header. To avoid this, make sure to
> > > clean-up the sched_flags field in sched_getattr() before returning to
> > > userspace.
> > >
> > > Signed-off-by: Quentin Perret <qperret@google.com>
> > > ---
> > > kernel/sched/core.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > > index 2d9ff40f4661..d8f489dcc383 100644
> > > --- a/kernel/sched/core.c
> > > +++ b/kernel/sched/core.c
> > > @@ -7535,6 +7535,7 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
> > > kattr.sched_priority = p->rt_priority;
> > > else
> > > kattr.sched_nice = task_nice(p);
> > > + kattr.sched_flags &= SCHED_FLAG_ALL;
> >
> > Maybe we can do this in the previous patch so that it's kept confined to
> > deadline bits?
>
> That works too, it just felt like this could happen again if we start
> using non-standard flags outside of deadline for any reason at some
> point in the future. But no strong opinion really.
Yeah, I also see this point. :)
So no prob with me to keep it in core.c as you do here.
Best,
Juri
next prev parent reply other threads:[~2021-07-28 12:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 10:11 [PATCH 0/2] A couple of sched_getattr() fixes for DL Quentin Perret
2021-07-27 10:11 ` [PATCH 1/2] sched/deadline: Fix reset_on_fork reporting of DL tasks Quentin Perret
2021-07-29 16:26 ` Dietmar Eggemann
2021-08-05 9:34 ` [tip: sched/core] " tip-bot2 for Quentin Perret
2021-07-27 10:11 ` [PATCH 2/2] sched: Don't report SCHED_FLAG_SUGOV in sched_getattr() Quentin Perret
2021-07-28 9:12 ` Juri Lelli
2021-07-28 9:39 ` Quentin Perret
2021-07-28 12:36 ` Juri Lelli [this message]
2021-07-29 17:21 ` Dietmar Eggemann
2021-07-29 17:28 ` Quentin Perret
2021-08-05 9:34 ` [tip: sched/core] " tip-bot2 for Quentin Perret
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