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Thu, 10 Apr 2025 19:07:50 +0000 (GMT) Message-ID: <567cb7ab-23d6-4cee-a915-c8cdac903ddd@linux.ibm.com> Date: Fri, 11 Apr 2025 00:37:49 +0530 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 13/15] block: remove several ->elevator_lock To: Ming Lei , Jens Axboe , linux-block@vger.kernel.org Cc: Shinichiro Kawasaki , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Christoph Hellwig References: <20250410133029.2487054-1-ming.lei@redhat.com> <20250410133029.2487054-14-ming.lei@redhat.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20250410133029.2487054-14-ming.lei@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: bQ5CDByL-jNrbD-QZOAaoCjf2vxlFsI2 X-Proofpoint-GUID: bQ5CDByL-jNrbD-QZOAaoCjf2vxlFsI2 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-10_05,2025-04-10_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 lowpriorityscore=0 clxscore=1015 malwarescore=0 spamscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 suspectscore=0 mlxlogscore=852 phishscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504100137 On 4/10/25 7:00 PM, Ming Lei wrote: > Both blk_mq_map_swqueue() and blk_mq_realloc_hw_ctxs() are only called > from queue initialization or updating nr_hw_queues code, in which > elevator switch can't happen any more. > > So remove these ->elevator_lock uses. > But what if blk_mq_map_swqueue runs in parallel, one context from blk_mq_init_allocated_queue and another from blk_mq_update_nr_hw_queues? It seems this is possible due to blk_mq_map_swqueue is invoked right after queue is added in tag-set from blk_mq_init_allocated_queue. Thanks, --Nilay