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Date: Wed, 5 Nov 2025 16:57:48 +0100
From: Frederic Weisbecker <frederic@kernel.org>
To: Phil Auld <pauld@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Danilo Krummrich <dakr@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Gabriele Monaco <gmonaco@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@redhat.com>, Jakub Kicinski <kuba@kernel.org>,
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Subject: Re: [PATCH 13/33] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset
Message-ID: <aQtz_ODTgiCGS_oB@localhost.localdomain>
References: <20251013203146.10162-1-frederic@kernel.org>
 <20251013203146.10162-14-frederic@kernel.org>
 <20251031125951.GA430420@pauld.westford.csb>
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In-Reply-To: <20251031125951.GA430420@pauld.westford.csb>

Le Fri, Oct 31, 2025 at 08:59:51AM -0400, Phil Auld a écrit :
> > +int housekeeping_update(struct cpumask *mask, enum hk_type type)
> > +{
> > +	struct cpumask *trial, *old = NULL;
> > +
> > +	if (type != HK_TYPE_DOMAIN)
> > +		return -ENOTSUPP;
> > +
> > +	trial = kmalloc(sizeof(*trial), GFP_KERNEL);
> > +	if (!trial)
> > +		return -ENOMEM;
> > +
> > +	cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), mask);
> > +	if (!cpumask_intersects(trial, cpu_online_mask)) {
> > +		kfree(trial);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!housekeeping.flags)
> > +		static_branch_enable(&housekeeping_overridden);
> > +
> > +	if (!(housekeeping.flags & BIT(type)))
> > +		old = housekeeping_cpumask_dereference(type);
> > +	else
> > +		WRITE_ONCE(housekeeping.flags, housekeeping.flags | BIT(type));
> 
> Isn't this backwards?   If the bit is not set you save old to free it
> and if the bit is set you set it again.

That's completely backward!

Thanks for pointing out!

-- 
Frederic Weisbecker
SUSE Labs