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Mon, 29 Dec 2025 16:37:31 -0800 (PST) Message-ID: <0f65c4fe-8b10-403d-b5b6-ed33fc4eb69c@kernel.dk> Date: Mon, 29 Dec 2025 17:37:29 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 09/33] block: Protect against concurrent isolated cpuset change To: Frederic Weisbecker , LKML Cc: =?UTF-8?Q?Michal_Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , 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 References: <20251224134520.33231-1-frederic@kernel.org> <20251224134520.33231-10-frederic@kernel.org> Content-Language: en-US From: Jens Axboe In-Reply-To: <20251224134520.33231-10-frederic@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/24/25 6:44 AM, Frederic Weisbecker wrote: > The block subsystem prevents running the workqueue to isolated CPUs, > including those defined by cpuset isolated partitions. Since > HK_TYPE_DOMAIN will soon contain both and be subject to runtime > modifications, synchronize against housekeeping using the relevant lock. > > For full support of cpuset changes, the block subsystem may need to > propagate changes to isolated cpumask through the workqueue in the > future. > > Signed-off-by: Frederic Weisbecker > --- > block/blk-mq.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 1978eef95dca..0037af1216f3 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -4257,12 +4257,16 @@ static void blk_mq_map_swqueue(struct request_queue *q) > > /* > * Rule out isolated CPUs from hctx->cpumask to avoid > - * running block kworker on isolated CPUs > + * running block kworker on isolated CPUs. > + * FIXME: cpuset should propagate further changes to isolated CPUs > + * here. > */ > + rcu_read_lock(); > for_each_cpu(cpu, hctx->cpumask) { > if (cpu_is_isolated(cpu)) > cpumask_clear_cpu(cpu, hctx->cpumask); > } > + rcu_read_unlock(); Want me to just take this one separately and get it out of your hair? Doesn't seem to have any dependencies. -- Jens Axboe