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charset=UTF-8 X-Lms-Return-Path: Message-Id: <1c739fcc-5132-4cb2-bf34-cec94de26509@fygo.io> References: Reply-To: yukuai@fygo.io To: "Yu Kuai" , , , , , , Subject: Re: [PATCH 0/8] blk-cgroup: remove queue_lock nesting from blkcg paths Date: Wed, 24 Jun 2026 14:57:59 +0800 Content-Transfer-Encoding: quoted-printable User-Agent: Mozilla Thunderbird Received: from [192.168.1.104] ([39.182.0.148]) by smtp.larksuite.com with ESMTPS; Wed, 24 Jun 2026 06:58:04 +0000 In-Reply-To: X-Rspam-User: X-Stat-Signature: jw8ewgy95xs1iiquy3mrx5ns6gp6th3t X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D2C0B1C0009 X-HE-Tag: 1782284290-628332 X-HE-Meta: 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 iiG7Zz1y kjQF8plug1pT8SnCh1l8t8Km4Kl/wntD0NufNr2c3FRiK+2ql+2ZgT0FG1D84gkawGuabQwgTC85fIIemEJAaKmso6eJx6G003egt8FsHWH06+Mmh5j8jmIYTBkaTfyQXyLv4ENhg4V0ghgfMOTDekE2yDa2OavBC6zRtJU/L9Cpnon7ohTUjG50Q/hhRZJNxvA44jVVCOgAKWgiTqYbCQCqEckQiAJTJKmWWdCGMYXPGaE52cori/wS0gT5YvJHwZx3DL/WJgG3wNYhG1uH0tkjyRFD64YZdKZdJBhTfhKCHX1QF2xVESnrcM7JGbw4G+xtO+ZbjaPYng28IKlnUkMKzLn8Ld/9TzP2vRuvRt6u3hfkVEuP3LiPpvQ9DONWT6cisMSyXyYa9sAelknEuHWGnW35zgiKNXU+dyIT6qdLXIH7sLzHhj8RVxPf4XG06qO41PZMsa9fhHQBxiiNtb7RKVFYo2pAVHIH/t7vrqnnxhqfr6JBKT6lFdyvW4sFNn6j0qREoYDsS08z5iOf6LNIqsyCHfVhoutt/q7EWrYuBNAxcbqqIRAuICRpALsYKAPfj/S50cT11xvIMf7+FuKTeFmUro7DySKWoPts1xETgKb2gdDqL5q2FOM1kIOPHbm+4oeNgCTcX1wJaShkE3lTL6J48aIJqE0MgVAzQzg49MdSL7ACa8uzZwYSrG0uJBSIlM36Acn9iX5A= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Friendly ping ... This set can still be applied cleanly for block-7.2 branch. =E5=9C=A8 2026/6/8 11:42, Yu Kuai =E5=86=99=E9=81=93: > From: Yu Kuai > > Hi, > > This series is the follow-up blk-cgroup locking cleanup on top of the > earlier blkg-list protection fixes, and prepares blk-cgroup to stop using > q->queue_lock as the global blkg lifetime/iteration lock. > > The current queue_lock based protection is hard to maintain because > queue_lock is used from hardirq and softirq completion paths, while some > blkcg cgroup file paths also need to iterate blkgs, print policy data, or > create blkgs from RCU-protected contexts. This series first tightens the > blkcg-side lifetime rules: > > - blkcg_print_stat() iterates blkgs under blkcg->lock with IRQs disabled. > - policy data freeing is delayed past an RCU grace period. > - blkcg_print_blkgs(), blkg lookup/create, bio association, page-IO > association, blkg destruction, and BFQ initialization stop nesting > queue_lock under RCU or blkcg->lock. > > Using blkcg->lock and RCU for blkcg-owned lists/data keeps the lock order > local to blk-cgroup and avoids extending queue_lock into cgroup file > iteration paths. It also makes the subsequent conversion to q->blkcg_mut= ex > possible without carrying forward queue_lock's interrupt-context > constraints. > > Yu Kuai (8): > blk-cgroup: protect iterating blkgs with blkcg->lock in > blkcg_print_stat() > blk-cgroup: delay freeing policy data after rcu grace period > blk-cgroup: don't nest queue_lock under rcu in blkcg_print_blkgs() > blk-cgroup: don't nest queue_lock under rcu in blkg_lookup_create() > blk-cgroup: don't nest queue_lock under rcu in bio_associate_blkg() > blk-cgroup: don't nest queue_lock under blkcg->lock in > blkcg_destroy_blkgs() > mm/page_io: don't nest queue_lock under rcu in > bio_associate_blkg_from_page() > block, bfq: don't grab queue_lock to initialize bfq > > block/bfq-cgroup.c | 17 ++++- > block/bfq-iosched.c | 5 -- > block/blk-cgroup-rwstat.c | 15 ++-- > block/blk-cgroup.c | 151 ++++++++++++++++++++++---------------- > block/blk-cgroup.h | 8 +- > block/blk-iocost.c | 22 ++++-- > block/blk-iolatency.c | 10 ++- > block/blk-throttle.c | 13 +++- > mm/page_io.c | 7 +- > 9 files changed, 158 insertions(+), 90 deletions(-) > > > base-commit: b23df513de562739af61fa61ba80ef5e8059a636 --=20 Thanks, Kuai