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From: Juri Lelli <>
To: Quentin Perret <>
Cc: Ingo Molnar <>,
	Peter Zijlstra <>,
	Vincent Guittot <>,
	Dietmar Eggemann <>,
	Steven Rostedt <>,
	Ben Segall <>, Mel Gorman <>,
	Daniel Bristot de Oliveira <>,,
Subject: Re: [PATCH v2] sched/deadline: Fix sched_getattr() for DL tasks
Date: Fri, 30 Jul 2021 11:22:18 +0200	[thread overview]
Message-ID: <YQPEygMj5ObRDLHG@localhost.localdomain> (raw)
In-Reply-To: <>


On 29/07/21 18:52, Quentin Perret wrote:
> In its current state, sched_getattr() can report incorrect sched_flags
> if called on a deadline task.
> Firstly, if the reset_on_fork flag is set on a deadline task using
> p->sched_reset_on_fork will be set but __setscheduler() will bail out
> early without updating the dl_se->flags. Consequently, if sched_getattr
> is then called on the same task, __getparam_dl() will override
> kattr.sched_flags with the now out-of-date copy in dl_se->flags and
> report a stale reset_on_fork value to userspace.
> And secondly, sched_getattr() currently reports SCHED_FLAG_SUGOV as set
> if called on a schedutil worker, despite this flag being a kernel-only
> value that is not exposed in UAPI headers.
> To fix both of these problems, make sure to only copy the flags that are
> relevant to sched_deadline to dl_se->flags, and filter them out when
> reporting them back to userspace.
> Signed-off-by: Quentin Perret <>

Looks good to me.

Acked-by: Juri Lelli <>


      reply	other threads:[~2021-07-30  9:22 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 17:52 Quentin Perret
2021-07-30  9:22 ` Juri Lelli [this message]

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