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Sun, 4 Jan 2026 16:39:53 +0000 (GMT) Message-ID: <7697d4c6-d3c5-4d0a-98a8-b6934f685e41@linux.ibm.com> Date: Sun, 4 Jan 2026 22:09:51 +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 v7 12/16] blk-iocost: fix incorrect lock order for rq_qos_mutex and freeze queue To: Yu Kuai , axboe@kernel.dk, linux-block@vger.kernel.org, tj@kernel.org, ming.lei@redhat.com References: <20251231085126.205310-1-yukuai@fnnas.com> <20251231085126.205310-13-yukuai@fnnas.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20251231085126.205310-13-yukuai@fnnas.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: nyRD1WK8CwGcCxfTKya4MVAr_Jn0hi9y X-Authority-Analysis: v=2.4 cv=Jvf8bc4C c=1 sm=1 tr=0 ts=695a97de cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=tJLSzyRPAAAA:8 a=VnNF1IyMAAAA:8 a=r2BwZxqds70EAL1L_7UA:9 a=QEXdDO2ut3YA:10 a=H0xsmVfZzgdqH4_HIfU3:22 X-Proofpoint-ORIG-GUID: nyRD1WK8CwGcCxfTKya4MVAr_Jn0hi9y X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTA0MDE1MSBTYWx0ZWRfX2XwaP5PsPk/u tbmr+TpRrSoveYXRtnwojd/wh2fcpSZX4ddIfPAZTHPRn87ziuqlNALoRoRxbtAav0qRygEW4mK jW+buR1eYCAtsJacy6zNGzjBcKnoznpOmmkxcFZ2nujF30L+h6eUv4PivFGRze1bwm2PfGMs7KU d3BDWFpF51kFHIGeDho9p/1IjyUKPd91rioGBGEqveUVYUKXDvjGBOH0WY8Mf39C4tl8zcpKf+Z 8F9d1DpInFCd7Q5eucRHUtFMb46Bdy95GziOAJG9xMjEBImCHDixUYXCN3ETEFNKvLhDUmGwASJ mTzDeAoKkpFS/5HCYMwkRwurieQYeL2+SZojbwFh1LBZmfszuqTtmN+uKTiLFJj74o/4ZOeinw/ D8xU3ukUM6rGkoq5kUnPZDvxJtsK/dPfiK34CSyLkM3TPeC6YdDIvSFQJYYbhvdXxwTy5hdveHR cmcTfknWuKpChOuCSZA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-04_05,2025-12-31_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 suspectscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 adultscore=0 spamscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601040151 On 12/31/25 2:21 PM, Yu Kuai wrote: > Like wbt, rq_qos_add() can be called from two path and the lock order > are inversely: > > - From ioc_qos_write(), queue is already frozen before rq_qos_add(); > - From ioc_cost_model_write(), rq_qos_add() is called directly; > > Fix this problem by converting to use blkg_conf_open_bdev_frozen() > from ioc_cost_model_write(), then since all rq_qos_add() callers > already freeze queue, convert to use rq_qos_add_frozen(). > > Signed-off-by: Yu Kuai Looks good to me: Reviewed-by: Nilay Shroff