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Fri, 11 Apr 2025 19:13:12 +0000 (GMT) Message-ID: <3c4350f4-4ab3-493f-b948-22f093e97d16@linux.ibm.com> Date: Sat, 12 Apr 2025 00:43:10 +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 04/15] block: prevent elevator switch during updating nr_hw_queues 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> <20250410133029.2487054-5-ming.lei@redhat.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20250410133029.2487054-5-ming.lei@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: mdAQq3KT7YsAn_bNAZ2rzn9oW8yJT4xy X-Proofpoint-ORIG-GUID: mdAQq3KT7YsAn_bNAZ2rzn9oW8yJT4xy 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=2025-04-11_07,2025-04-10_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 adultscore=0 spamscore=0 bulkscore=0 mlxlogscore=907 clxscore=1015 suspectscore=0 malwarescore=0 mlxscore=0 impostorscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504110122 On 4/10/25 7:00 PM, Ming Lei wrote: > @@ -5081,7 +5087,18 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, > void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) > { > mutex_lock(&set->tag_list_lock); > + /* > + * Mark us in updating nr_hw_queues for preventing switching > + * elevator > + * > + * Elevator switch code can _not_ acquire ->tag_list_lock > + */ > + set->flags |= BLK_MQ_F_UPDATE_HW_QUEUES; > + synchronize_srcu(&set->update_nr_hwq_srcu); > + > __blk_mq_update_nr_hw_queues(set, nr_hw_queues); > + > + set->flags &= BLK_MQ_F_UPDATE_HW_QUEUES; I think here we want to clear BLK_MQ_F_UPDATE_HW_QUEUES, so we need to have set->flags updated as below: set->flags &= ~BLK_MQ_F_UPDATE_HW_QUEUES; Thanks, --Nilay