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Sun, 4 Jan 2026 16:38:50 +0000 (GMT) Message-ID: <4638071a-df70-4295-8082-eb5a2957501e@linux.ibm.com> Date: Sun, 4 Jan 2026 22:08:49 +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 v7 09/16] blk-throttle: fix possible deadlock for fs reclaim under rq_qos_mutex 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> <20251231085126.205310-10-yukuai@fnnas.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20251231085126.205310-10-yukuai@fnnas.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=OdmVzxTY c=1 sm=1 tr=0 ts=695a979f cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=tJLSzyRPAAAA:8 a=VnNF1IyMAAAA:8 a=DuAXc3mGnazSLxeS_qgA:9 a=QEXdDO2ut3YA:10 a=H0xsmVfZzgdqH4_HIfU3:22 X-Proofpoint-GUID: k-Ir46rHVsJAp5s-YngRgZ2E4Cv_Uv2c X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTA0MDE1MSBTYWx0ZWRfX13Q2g9k9R4L8 vNrGhIA8W3qglQ3HJanyo/44NjyhbgVTCFXFhemd9e7OkDaHdiRw0Y8He/k1LQf8m4DhfUtUVRY pVfzNWUKvWPII3Wsup2jCWgvImjicWtstv1PJSjzHjbMyaGzjtB8wfbTRq7h0ipCjmGrU9NVQ6q 4uMxFr5W9aB9AOmpkEnctxbVsmSHl7S/t1ypSZl+fPFHPqCqqFe1liTlZ/8Rawy+7CkcG53J6CT zjOk/w7t524FiWX/r2nPAqdUDehFKE3PAb6BqK0FI5fjxm9J/25z299gY5kDAu6G0RZtysurH48 XgZHF2zgVHQl+NnepLbMnqmy3gPhnH7jwIxEHu/6WzSuQLCtFy06Fb2oT73Bn2WK/MY5P3ws6hj YWKHtr0BCgnXERBJcnGFW7ofG0uTWNGNeVEfzS9dHk9UZiuixDBmPgg2CLyQj04VyqJlyspRwfW ys6OpeJvCuB4iPfQD6Q== X-Proofpoint-ORIG-GUID: k-Ir46rHVsJAp5s-YngRgZ2E4Cv_Uv2c 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 spamscore=0 clxscore=1015 phishscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 suspectscore=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: > blk_throtl_init() can be called with rq_qos_mutex held from blkcg > configuration, and fs reclaim can be triggered because GFP_KERNEL is used > to allocate memory. This can deadlock because rq_qos_mutex can be held > with queue frozen. > > Fix the problem by using blkg_conf_open_bdev_frozen(), also remove > useless queue frozen from blk_throtl_init(). > > Signed-off-by: Yu Kuai Looks good to me: Reviewed-by: Nilay Shroff