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Mon, 4 Aug 2025 12:21:29 +0000 (GMT) From: Nilay Shroff To: linux-block@vger.kernel.org Cc: axboe@kernel.dk, kch@nvidia.com, shinichiro.kawasaki@wdc.com, hch@lst.de, ming.lei@redhat.com, gjoyce@ibm.com Subject: [PATCH 2/2] block: clear QUEUE_FLAG_QOS_ENABLED in rq_qos_del() Date: Mon, 4 Aug 2025 17:51:11 +0530 Message-ID: <20250804122125.3271397-3-nilay@linux.ibm.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250804122125.3271397-1-nilay@linux.ibm.com> References: <20250804122125.3271397-1-nilay@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA0MDA2OCBTYWx0ZWRfX/UdbL8snyo2D 4oL4fqgGIBagCwPvJAaiMX9HOtSw3mxzOKd8LDdIm4ieaMUo1APTzBj3qG3XxQA+wbKUP8wmq5w CSqu4mONed8GPR1vupaKdgpbLXZ/XtNltswrleK0TTYNepxBW8Qlq6UWO/23DNUG+sM4t4TjgxN sPtbzVOsZUFGJ+LVgzXLZAym60F38Xx/BvZEdAC/rmS9I7eRBaXVKDwdSWmuunSjp9XDUa0ikPI q6kToeh+vjsG4mm6PbJCzeyNyTRuuFOQS7NZZcAC4iD9iOyozHPB6Y4Zn4ny1F80077RTS71IwS ijfnJC3MGJwGxhxCLptQjBwoXsC5PoQaJ7ptn65h3YIqcTJB/EMDc2r1FEPwI8CHE4Ao3bO4Ygr 9asiXOTXjcQkYb18InMkeFoIpIcoF8ihNZS0A5rs9/T/BKW2NSsqmhNeLSY+zLSbooF0t5iA X-Authority-Analysis: v=2.4 cv=Qp9e3Uyd c=1 sm=1 tr=0 ts=6890a5ce cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=2OwXVqhp2XgA:10 a=VnNF1IyMAAAA:8 a=UJK3Dzy7yT7oL-vBR3kA:9 X-Proofpoint-ORIG-GUID: RSfGRkyKBqlzWGAPv7miOPzH1dqQuKUm X-Proofpoint-GUID: RSfGRkyKBqlzWGAPv7miOPzH1dqQuKUm X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-04_05,2025-08-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 phishscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 mlxlogscore=931 spamscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2508040068 When a QoS function is removed via rq_qos_del(), and it happens to be the last QoS function on the request queue, q->rq_qos becomes NULL. In this case, the QUEUE_FLAG_QOS_ENABLED bit should also be cleared to reflect that no QoS hooks remain active. This patch ensures that the QUEUE_FLAG_QOS_ENABLED flag is cleared if the queue no longer has any associated rq_qos policies. Failing to do so could cause unnecessary dereferences of a now-null q->rq_qos pointer in the I/O path. Signed-off-by: Nilay Shroff --- block/blk-rq-qos.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c index 460c04715321..654478dfbc20 100644 --- a/block/blk-rq-qos.c +++ b/block/blk-rq-qos.c @@ -375,6 +375,8 @@ void rq_qos_del(struct rq_qos *rqos) break; } } + if (!q->rq_qos) + blk_queue_flag_clear(QUEUE_FLAG_QOS_ENABLED, q); blk_mq_unfreeze_queue(q, memflags); mutex_lock(&q->debugfs_mutex); -- 2.50.1