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Mon, 20 Apr 2026 06:12:03 -0700 (PDT) From: Marco Crivellari To: atomlin@atomlin.com Cc: James.Bottomley@HansenPartnership.com, MPT-FusionLinux.pdl@broadcom.com, aacraid@microsemi.com, akpm@linux-foundation.org, axboe@kernel.dk, bigeasy@linutronix.de, chandrakanth.patil@broadcom.com, chenridong@huawei.com, chjohnst@gmail.com, frederic@kernel.org, hare@suse.de, hch@lst.de, jinpu.wang@cloud.ionos.com, juri.lelli@redhat.com, kashyap.desai@broadcom.com, kbusch@kernel.org, kch@nvidia.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, liyihang9@h-partners.com, longman@redhat.com, martin.petersen@oracle.com, maz@kernel.org, megaraidlinux.pdl@broadcom.com, ming.lei@redhat.com, mingo@redhat.com, mpi3mr-linuxdrv.pdl@broadcom.com, mproche@gmail.com, mst@redhat.com, neelx@suse.com, nick.lange@gmail.com, peterz@infradead.org, ranjan.kumar@broadcom.com, ruanjinjie@huawei.com, sagi@grimberg.me, sathya.prakash@broadcom.com, sean@ashe.io, shivasharan.srikanteshwara@broadcom.com, sreekanth.reddy@broadcom.com, steve@abita.co, suganath-prabu.subramani@broadcom.com, sumit.saxena@broadcom.com, tglx@kernel.org, tom.leiming@gmail.com, vincent.guittot@linaro.org, virtualization@lists.linux.dev, wagi@kernel.org, yphbchou0911@gmail.com Subject: Re: [PATCH v11 03/13] lib/group_cpus: Add group_mask_cpus_evenly() Date: Mon, 20 Apr 2026 15:11:52 +0200 Message-ID: <20260420131152.243488-1-marco.crivellari@suse.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260416192942.1243421-4-atomlin@atomlin.com> References: <20260416192942.1243421-4-atomlin@atomlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi, Maybe I'm missing some background here, I noticed group_mask_cpus_evenly() is called inside irq_create_affinity_masks() and the "numgrps" it is this_vecs in the latter. Looking to group_cpus_evenly(), seems it is possible to have this_vecs equals to 0, indeed this function return NULL if numgrps == 0: >488 struct cpumask *group_cpus_evenly(unsigned int numgrps, unsigned int *nummasks) >489 { >[...] >495 >496 if (numgrps == 0) >497 return NULL; Without it, I guess the kmalloc() in `group_mask_cpus_evenly()` will return ZERO_SIZE_PTR: >+struct cpumask *group_mask_cpus_evenly(unsigned int numgrps, >+ const struct cpumask *mask, >+ unsigned int *nummasks) >+{ > > [...] > >+ masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL); >+ if (!masks) >+ goto fail_node_to_cpumask; and this value is then passed to `__group_cpus_evenly()`. Should this check be added or it is not needed? Or maybe rely on `ZERO_OR_NULL_PTR()` ? Thanks! -- Marco Crivellari SUSE Labs