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Fri, 25 Apr 2025 13:10:45 +0000 (GMT) Message-ID: Date: Fri, 25 Apr 2025 18:40:44 +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 V3 20/20] block: move wbt_enable_default() out of queue freezing from sched ->exit() To: Ming Lei , Jens Axboe , linux-block@vger.kernel.org Cc: Shinichiro Kawasaki , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Christoph Hellwig References: <20250424152148.1066220-1-ming.lei@redhat.com> <20250424152148.1066220-21-ming.lei@redhat.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20250424152148.1066220-21-ming.lei@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=dbeA3WXe c=1 sm=1 tr=0 ts=680b89d9 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=XR8D0OoHHMoA:10 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=gI2BpVEeF5L0_ZfhzhMA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNDI1MDA5NCBTYWx0ZWRfX8ABsaGhjQY7A p8/K2VVUohtjD/fazxB5ctcvcuygUG6hkgg3CxbyGk5s8VvzmCTtv5FrX1skIicqLHPSlOfAugF OckNcCNkG3/zVe4VtehACStujRRcrTuOcPvovnox5dsgemi/9J/bZVU2IFxGr8dYvFC5szzNG+q 1D26Uquzg5IKBdyG7ZSh5o9eoQWbXN5Nh45yl1qXjPW5jWYmMyJ/ve403t6ws+HGEtpAY8exNgj Vo/368a8dAHxbfZTaX9z3n088wZl+w9h0DMXXqRU7tgw7OcmNbKLP+4Zg/drruK3HswzO7vV8pn cPPtyLPiysP5QHe68ul7k89I9asR2bYZBQb93NzLVhtQ8ex1tboVQA4dSWXdpq+YpQ+bEkEH/gh CxbshiNwYri191ZyWakT4G/JhWWnQA2w6Bv2cuzdMTquSF0CzM5uv3HNTAXkE2598TXJA0yk X-Proofpoint-ORIG-GUID: 0XEDroFzj7abyXx7nvC72P5hNwLcpleI X-Proofpoint-GUID: 0XEDroFzj7abyXx7nvC72P5hNwLcpleI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-04-25_03,2025-04-24_02,2025-02-21_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 suspectscore=0 priorityscore=1501 impostorscore=0 spamscore=0 mlxscore=0 lowpriorityscore=0 bulkscore=0 adultscore=0 mlxlogscore=999 clxscore=1015 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2504070000 definitions=main-2504250094 On 4/24/25 8:51 PM, Ming Lei wrote: > scheduler's ->exit() is called with queue frozen and elevator lock is held, and > wbt_enable_default() can't be called with queue frozen, otherwise the > following lockdep warning is triggered: > > #6 (&q->rq_qos_mutex){+.+.}-{4:4}: > #5 (&eq->sysfs_lock){+.+.}-{4:4}: > #4 (&q->elevator_lock){+.+.}-{4:4}: > #3 (&q->q_usage_counter(io)#3){++++}-{0:0}: > #2 (fs_reclaim){+.+.}-{0:0}: > #1 (&sb->s_type->i_mutex_key#3){+.+.}-{4:4}: > #0 (&q->debugfs_mutex){+.+.}-{4:4}: > > Fix the issue by moving wbt_enable_default() out of bfq's exit(), and > call it from elevator_change_done(). > > Meantime add disk->rqos_state_mutex for covering wbt state change, which > matches the purpose more than ->elevator_lock. > > Signed-off-by: Ming Lei Looks good to me: Reviewed-by: Nilay Shroff