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From: Andrea Righi <arighi@nvidia.com>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	Tejun Heo <tj@kernel.org>,
	Patrick Bellasi <patrick.bellasi@arm.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 0/2] sched: Fix SCHED_FLAG_KEEP_PARAMS side effects
Date: Thu, 30 Jul 2026 07:50:09 +0200	[thread overview]
Message-ID: <20260730055011.2267333-1-arighi@nvidia.com> (raw)

SCHED_FLAG_KEEP_PARAMS allows sched_setattr() to update generic task
attributes while retaining the task's existing scheduling parameters and
class.

Two paths in __sched_setscheduler() still act on the requested policy
before the guarded parameter update. One marks the operation as a class
change and invokes class transition callbacks even though the class remains
unchanged. The other performs deadline admission control and can account
bandwidth for a non-deadline task that never enters the deadline class.

Prevent both side effects when SCHED_FLAG_KEEP_PARAMS is set.

Andrea Righi (2):
      sched: Skip class callbacks with SCHED_FLAG_KEEP_PARAMS
      sched/deadline: Skip bandwidth accounting with SCHED_FLAG_KEEP_PARAMS

 kernel/sched/syscalls.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

base-commit: bafb78898eb70fcaa979608a2d7ae9bad86124a1

             reply	other threads:[~2026-07-30  5:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-30  5:50 Andrea Righi [this message]
2026-07-30  5:50 ` [PATCH 1/2] sched: Skip class callbacks with SCHED_FLAG_KEEP_PARAMS Andrea Righi
2026-07-30  7:29   ` K Prateek Nayak
2026-07-30  8:57     ` Andrea Righi
2026-07-30  9:57     ` Peter Zijlstra
2026-07-30 11:42       ` Andrea Righi
2026-07-30  5:56 ` [PATCH 2/2] sched/deadline: Skip bandwidth accounting " Andrea Righi
2026-07-30 10:04   ` Peter Zijlstra
2026-07-30  9:32 ` [PATCH 0/2] sched: Fix SCHED_FLAG_KEEP_PARAMS side effects Peter Zijlstra
2026-07-30  9:52   ` Peter Zijlstra

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