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Wed, 2 Apr 2025 13:43:58 +0000 (GMT) Message-ID: <089a8cf5-bc01-468f-ab96-f04448e034ae@linux.ibm.com> Date: Wed, 2 Apr 2025 19:13:56 +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 3/3] block: use blk_mq_no_io() for avoiding lock dependency To: Ming Lei , Jens Axboe , linux-block@vger.kernel.org Cc: =?UTF-8?Q?Valdis_Kl=C4=93tnieks?= , Christoph Hellwig , syzbot+4c7e0f9b94ad65811efb@syzkaller.appspotmail.com References: <20250402043851.946498-1-ming.lei@redhat.com> <20250402043851.946498-4-ming.lei@redhat.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20250402043851.946498-4-ming.lei@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: PhUA9BzmKXO8fk36eE-5fXcQ9CjuQOve X-Proofpoint-GUID: PhUA9BzmKXO8fk36eE-5fXcQ9CjuQOve 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=2025-04-02_05,2025-04-02_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=433 impostorscore=0 bulkscore=0 malwarescore=0 clxscore=1011 suspectscore=0 priorityscore=1501 adultscore=0 phishscore=0 mlxscore=0 lowpriorityscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504020085 On 4/2/25 10:08 AM, Ming Lei wrote: > Use blk_mq_no_io() to prevent IO from entering queue for avoiding lock > dependency between freeze lock and elevator lock, and we have got many > such reports: > > Reported-by: syzbot+4c7e0f9b94ad65811efb@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/linux-block/67e6b425.050a0220.2f068f.007b.GAE@google.com/ > Reported-by: Valdis Klētnieks > Closes: https://lore.kernel.org/linux-block/7755.1743228130@turing-police/#t > Signed-off-by: Ming Lei I tested this series on my system and this works well as we cut dependency between ->elevator_lock and ->freeze_lock. However don't we plan to now model blk_mq_enter_no_io and blk_mq_exit_no_io as lock/unlock for supporting lockdep? Maybe we don't. Overall changes looks good to me: Reviewed-by: Nilay Shroff