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Mon, 8 Sep 2025 07:36:35 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id iptWBIOHvmjwRAAAD6G6ig (envelope-from ); Mon, 08 Sep 2025 07:36:35 +0000 Date: Mon, 8 Sep 2025 09:36:34 +0200 From: Daniel Wagner To: linux-nvme@lists.infradead.org Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , "Michael S. Tsirkin" , Aaron Tomlin , "Martin K. Petersen" , Thomas Gleixner , Costa Shulyupin , Juri Lelli , Valentin Schneider , Waiman Long , Ming Lei , Frederic Weisbecker , Mel Gorman , Hannes Reinecke , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, megaraidlinux.pdl@broadcom.com, linux-scsi@vger.kernel.org, storagedev@microchip.com, virtualization@lists.linux.dev, GR-QLogic-Storage-Upstream@marvell.com Subject: Re: [PATCH v8 10/12] blk-mq: use hk cpus only when isolcpus=io_queue is enabled Message-ID: References: <20250905-isolcpus-io-queues-v8-0-885984c5daca@kernel.org> <20250905-isolcpus-io-queues-v8-10-885984c5daca@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250905-isolcpus-io-queues-v8-10-885984c5daca@kernel.org> X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[25]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Level: X-Spam-Score: -4.30 On Fri, Sep 05, 2025 at 04:59:56PM +0200, Daniel Wagner wrote: > void blk_mq_map_queues(struct blk_mq_queue_map *qmap) > { > - const struct cpumask *masks; > + struct cpumask *masks __free(kfree) = NULL; > + const struct cpumask *constraint; > unsigned int queue, cpu, nr_masks; > + cpumask_var_t active_hctx; > > + if (!zalloc_cpumask_var(&active_hctx, GFP_KERNEL)) > + goto fallback; > + > + free_cpumask_var(active_hctx); > + > + return; > + > +free_fallback: > + free_cpumask_var(active_hctx); > + > +fallback: > + blk_mq_map_fallback(qmap); I am not so happy that the cpumask_var_t and __free doesn't work to together at this point due to the 'evil way' how cpumask_var_t is defined: ifdef CONFIG_CPUMASK_OFFSTACK typedef struct cpumask *cpumask_var_t; #else typedef struct cpumask cpumask_var_t[1]; #endif /* CONFIG_CPUMASK_OFFSTACK */ In the previous version I used cpumask_var_t active_hctx __free(free_cpumask_var) = NULL; which resulted in a way cleaner code. Though the kernel test robot complained with >> block/blk-mq-cpumap.c:155:16: error: array initializer must be an initializer list 155 | cpumask_var_t active_hctx __free(free_cpumask_var) = NULL; I try to figure out if it's possible to get this somehow working with some witchcraft (aka pre compiler magic).