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[2001:8b0:10b:1231::1]) by mx.google.com with ESMTPS id f125si83143415jaf.28.2019.07.30.01.11.37 for (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 30 Jul 2019 01:11:37 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) client-ip=2001:8b0:10b:1231::1; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=rxPQWpq1; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=lqG3hFLeHki6KlZNi6gozV3r9j/aZGFzc0fdJeJSVQ8=; b=rxPQWpq1LSCp6jnJK/v6L8dDR SkDfaijqdixP9Xmv7Riil22otsXN/ASK8qonDt1a1WnmCwcZFzOTSgAbcTOGAJ/q0YjwnjWVOAN4J aQItm82TxPGN0WVkOpGnPl0gdgabuNsroTPsKVPIGkdefwHCL43Mywg9MUHzTccgCcvBp/fp4Tg4Y yb89urip9Lk2Qp+GyN86WBbHtK6btdzda9xLD4lNnQyxBqeCeVecQ6vHWKegBrGJD6R9nuf6igjct DKTn0E8lGqly9r6I8JgKv/fXzc1I4FI5mzOw56W98AiFk6F9PGvDdRWJkXs8fM1iS6LW9Cqh9J+Sr mV+nqySTw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hsNEB-0005KX-Sn; Tue, 30 Jul 2019 08:11:24 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A37B120D27EAA; Tue, 30 Jul 2019 10:11:22 +0200 (CEST) Date: Tue, 30 Jul 2019 10:11:22 +0200 From: Peter Zijlstra To: Suren Baghdasaryan Cc: mingo@redhat.com, lizefan@huawei.com, hannes@cmpxchg.org, axboe@kernel.dk, dennis@kernel.org, dennisszhou@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, Nick Kralevich , Thomas Gleixner Subject: Re: [PATCH 1/1] psi: do not require setsched permission from the trigger creator Message-ID: <20190730081122.GH31381@hirez.programming.kicks-ass.net> References: <20190730013310.162367-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190730013310.162367-1-surenb@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jul 29, 2019 at 06:33:10PM -0700, Suren Baghdasaryan wrote: > When a process creates a new trigger by writing into /proc/pressure/* > files, permissions to write such a file should be used to determine whether > the process is allowed to do so or not. Current implementation would also > require such a process to have setsched capability. Setting of psi trigger > thread's scheduling policy is an implementation detail and should not be > exposed to the user level. Remove the permission check by using _nocheck > version of the function. > > Suggested-by: Nick Kralevich > Signed-off-by: Suren Baghdasaryan > --- > kernel/sched/psi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c > index 7acc632c3b82..ed9a1d573cb1 100644 > --- a/kernel/sched/psi.c > +++ b/kernel/sched/psi.c > @@ -1061,7 +1061,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, > mutex_unlock(&group->trigger_lock); > return ERR_CAST(kworker); > } > - sched_setscheduler(kworker->task, SCHED_FIFO, ¶m); > + sched_setscheduler_nocheck(kworker->task, SCHED_FIFO, ¶m); ARGGH, wtf is there a FIFO-99!! thread here at all !? > kthread_init_delayed_work(&group->poll_work, > psi_poll_work); > rcu_assign_pointer(group->poll_kworker, kworker); > -- > 2.22.0.709.g102302147b-goog >