| From: |
| Yu Kuai <yukuai-AT-kernel.org> |
| To: |
| nilay-AT-linux.ibm.com, tom.leiming-AT-gmail.com, bvanassche-AT-acm.org, tj-AT-kernel.org, josef-AT-toxicpanda.com, axboe-AT-kernel.dk, yukuai-AT-fygo.io |
| Subject: |
| [PATCH 0/8] blk-cgroup: remove queue_lock nesting from blkcg paths |
| Date: |
| Mon, 08 Jun 2026 11:42:41 +0800 |
| Message-ID: |
| <cover.1780621988.git.yukuai@fygo.io> |
| Cc: |
| akpm-AT-linux-foundation.org, chrisl-AT-kernel.org, kasong-AT-tencent.com, shikemeng-AT-huaweicloud.com, nphamcs-AT-gmail.com, bhe-AT-redhat.com, baohua-AT-kernel.org, youngjun.park-AT-lge.com, cgroups-AT-vger.kernel.org, linux-block-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org, linux-mm-AT-kvack.org |
| Archive-link: |
| Article |
From: Yu Kuai <yukuai@fygo.io>
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_mutex
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
--
2.51.0
