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Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Waiman Long , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 13/33] sched/isolation: Convert housekeeping cpumasks to rcu pointers Message-ID: <20260107115653.GA196631@kernel.org> References: <20260101221359.22298-1-frederic@kernel.org> <20260101221359.22298-14-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260101221359.22298-14-frederic@kernel.org> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 5065414000D X-Stat-Signature: ohjpgd5cy4g8sz57kyhq5bifjhd17spc X-Rspam-User: X-HE-Tag: 1767787024-691976 X-HE-Meta: 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 /nwQhi07 9BuXOQEo7CQcgMppKJNFfZ0fCM2+rFA5ROE0f+WOUhI4u5E3mZPGMgR6PYXW7nY2KO3y+6wij+R4JTwnMpGMUhBWeETpUVUFKbTuP6fo4C7kaDbh5EhCP9lLKfySeu34JN2vHdTlOeMdivhmOoGx7pJ1apBEXxY5yUKSpWxNRIY2g9xKgR/7ITu5imopQYLUanxigf+2bjfdzCH4rTumRL9e1Uuux9vjlWWKGxHrOUgFlzj7/aBQHs6Y15zS8MEX2BYGqeZvLG3oJ6D1ZK7htQI/gpQ== 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: List-Subscribe: List-Unsubscribe: On Thu, Jan 01, 2026 at 11:13:38PM +0100, Frederic Weisbecker wrote: > HK_TYPE_DOMAIN's cpumask will soon be made modifiable by cpuset. > A synchronization mechanism is then needed to synchronize the updates > with the housekeeping cpumask readers. > > Turn the housekeeping cpumasks into RCU pointers. Once a housekeeping > cpumask will be modified, the update side will wait for an RCU grace > period and propagate the change to interested subsystem when deemed > necessary. > > Signed-off-by: Frederic Weisbecker > --- > kernel/sched/isolation.c | 58 +++++++++++++++++++++++++--------------- > kernel/sched/sched.h | 1 + > 2 files changed, 37 insertions(+), 22 deletions(-) > > diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c > index 11a623fa6320..83be49ec2b06 100644 > --- a/kernel/sched/isolation.c > +++ b/kernel/sched/isolation.c > @@ -21,7 +21,7 @@ DEFINE_STATIC_KEY_FALSE(housekeeping_overridden); > EXPORT_SYMBOL_GPL(housekeeping_overridden); > > struct housekeeping { > - cpumask_var_t cpumasks[HK_TYPE_MAX]; > + struct cpumask __rcu *cpumasks[HK_TYPE_MAX]; > unsigned long flags; > }; > > @@ -33,17 +33,28 @@ bool housekeeping_enabled(enum hk_type type) > } > EXPORT_SYMBOL_GPL(housekeeping_enabled); > > +const struct cpumask *housekeeping_cpumask(enum hk_type type) > +{ > + if (static_branch_unlikely(&housekeeping_overridden)) { > + if (housekeeping.flags & BIT(type)) { > + return rcu_dereference_check(housekeeping.cpumasks[type], 1); > + } > + } > + return cpu_possible_mask; > +} > +EXPORT_SYMBOL_GPL(housekeeping_cpumask); > + Hi Frederic, I think this patch should also update the access to housekeeping.cpumasks in housekeeping_setup(), on line 200, to use housekeeping_cpumask(). As is, sparse flags __rcu a annotation miss match there. kernel/sched/isolation.c:200:80: warning: incorrect type in argument 3 (different address spaces) kernel/sched/isolation.c:200:80: expected struct cpumask const *srcp3 kernel/sched/isolation.c:200:80: got struct cpumask [noderef] __rcu * ...