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Fri, 18 Sep 2026 05:52:41 +0000 (GMT) Received: from [9.61.58.220] (unknown [9.61.58.220]) by smtpav06.wdc07v.mail.ibm.com (Postfix) with ESMTP; Fri, 18 Sep 2026 05:52:41 +0000 (GMT) Message-ID: <1742b0d0-fbdb-433b-b2c9-b47b5cfd7666@linux.ibm.com> Date: Fri, 18 Sep 2026 11:22:39 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/3] blk-cgroup: move async bio punt state to blkcg To: Yu Kuai , Jens Axboe , Josef Bacik , Tejun Heo , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Jonathan Corbet , Shuah Khan , Randy Dunlap , Coly Li , Kent Overstreet , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , Song Liu , Li Nan , Xiao Ni , Andreas Gruenbacher , Matthew Wilcox , Jan Kara , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt Cc: Yu Kuai , Christoph Hellwig , Tao Cui , linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@lists.linux.dev, linux-raid@vger.kernel.org, gfs2@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev References: <20260918041744.1526924-1-yukuai@kernel.org> <20260918041744.1526924-4-yukuai@kernel.org> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20260918041744.1526924-4-yukuai@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE4MDA3MiBTYWx0ZWRfX/teiT0wiHNSW JEvRLv8jYQnWWkxliGMH7Y5gxw8A38G2pBCriGrXSm3DN6Pr3l9Oia/Cs3vbs5x2dSUFWw1cfFz f6YEK9tOomOpksip3Jp/NjjN7rrYdt/gOI5v+6Y8AX7cViJK8cnyaAE3PjMik7w12aaXKvh6tPK tFBlkzqye1G3IuT9fAG8wstP9g6OAj+fQK4ugA5oL55w2miRU2d/M5YZzNY15Wjk04uncsH6aDp pnj11j8nfR0QxLHiscSmDcegPweYS/JObE2+bA7JB/xXyGgpQjesnbr/WvDVc+wx6dyVbrWXmva TRZBv+CiIDmwlROqGoPTmI8+6j49IF5vWsKy4421LSK4L8hh5RZqcbHHtqWWNbP4U/H4xAE0VIg qjhdgXfijXio3Cfv4RwZ0wphiapFt2dpjyauojKMPHivJdWmZuJs2lOfIk/cS3ryMpVrfiI0Gg9 /PO92Nr18Ody/I9Qj1g== X-Proofpoint-ORIG-GUID: IQzOuQqhULLvUviFRAhVAHKgtdnFYey7 X-Proofpoint-GUID: ZGCkVPtmRng54Q_CssYM4zmrTg3B8e93 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE4MDA3MiBTYWx0ZWRfX7hqucrhMwMz+ TMaoTQdDqBi4VtgFdBweWtZanWLjNVsk/ptq6fmVuMGXmra8Z54mRVbadv0oTv0nx+NSQH+0ts1 oIkWCJgjmb268QlqzkGvSbLj1oWUnos= X-Authority-Analysis: v=2.4 cv=cY9HPXDM c=1 sm=1 tr=0 ts=6aacd1ba cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=N7Slw706a9Tpp8ivUyUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-18_01,2026-09-16_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 bulkscore=0 clxscore=1015 suspectscore=0 impostorscore=0 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609180072 On 9/18/26 9:47 AM, Yu Kuai wrote: > From: Yu Kuai > > blkcg_punt_bio_submit() currently queues punted bios on blkg->async_bios, > so it has to call bio_blkg() to find or create a queue-local blkg. Bios > now carry and pin the blkcg css, so punted bio lifetime no longer needs to > be anchored by a blkg. > > Keeping the punt state in blkg can instantiate a blkg even when no blkcg > policy is enabled, just to bounce submission from a shared kthread. Move > async_bio_lock, async_bios and async_bio_work to struct blkcg, and queue > punted bios on bio_blkcg() for non-root cgroups. Root or unassociated bios > are submitted directly. > > This preserves the priority-inversion avoidance while preventing > blkcg_punt_bio_submit() from creating blkgs that are not needed by any > policy. > > Signed-off-by: Yu Kuai Looks good to me. Reviewed-by: Nilay Shroff