Documentation/admin-guide/cgroup-v2.rst | 2 +- block/bfq-cgroup.c | 16 +- block/bfq-iosched.c | 19 +- block/bio.c | 22 +- block/blk-cgroup-fc-appid.c | 10 +- block/blk-cgroup.c | 348 ++++++++++++++---------- block/blk-cgroup.h | 82 ++++-- block/blk-core.c | 9 +- block/blk-crypto-fallback.c | 2 +- block/blk-iocost.c | 12 +- block/blk-iolatency.c | 11 +- block/blk-ioprio.c | 2 +- block/blk-throttle.c | 2 +- block/blk-throttle.h | 2 +- drivers/md/bcache/request.c | 2 +- drivers/md/dm.c | 2 +- drivers/md/md.c | 2 +- drivers/nvdimm/nd_virtio.c | 2 +- fs/gfs2/lops.c | 3 +- include/linux/bio.h | 26 +- include/linux/blk_types.h | 9 +- include/linux/blkdev.h | 2 + include/linux/writeback.h | 2 +- mm/page_io.c | 13 +- 24 files changed, 357 insertions(+), 245 deletions(-)
From: Yu Kuai <yukuai@fygo.io>
This RFC remains a preparatory series for the blkcg_mutex conversion
proposed in the related blkcg_mutex RFC v2 series [1]. That conversion
moves queue-local blkg topology synchronization from q->queue_lock to
q->blkcg_mutex, which is awkward while bios directly store queue-local
blkg references.
v1 made the stored bio association queue-independent by replacing bi_blkg
with bi_blkcg, but a bio-owned blkg reference still had to be recovered by
looking up the bio's blkcg and current request_queue. Tao Cui reported that
cgroup removal deletes a dying blkg from the per-blkcg radix tree before a
throttled bio drops its reference. A later lookup for that pinned blkg then
fails, triggers the warning in bio_pinned_blkg(), and leaks the reference.
v2 makes request_queue the authoritative lookup owner before converting the
bio association. A queue-owned rhashtable, keyed by the blkcg CSS ID, keeps
dying blkgs discoverable until their references drain while q->blkg_list
remains available for ordered walks. The bio conversion then stores and
pins the blkcg CSS, lazily creates a blkg only for users which need one, and
uses lookup-only access for completion and accounting paths which already
own a blkg reference. Async bio punt state is finally moved from blkg to
blkcg so punting alone does not instantiate a queue-local blkg.
Changes since v1:
- Add patch 1 to wait for every old blkg to leave q->blkg_list before a
shared request_queue is rebound, instead of treating root_blkg == NULL
as completion of asynchronous blkg teardown.
- Add patch 2 to replace the per-blkcg radix tree and lookup hint with a
request_queue rhashtable keyed by blkcg->css.id, as suggested by
Christoph Hellwig. Keep dying pinned blkgs in the hash until
blkg_release() so bio-owned references remain discoverable.
- Fold the v1 helper-only patch into patch 3, as suggested by Jan Kara and
Christoph Hellwig, and make bio_blkcg() naturally return NULL for an
unassociated bio.
- Rework patch 3 so blkg_lookup_create() acquires the bio-owned reference,
falls back to a live parent when creation or tryget fails, and updates
bi_blkcg when the returned blkg belongs to an ancestor.
- Make bio_blkg_lookup() lookup-only: it returns NULL unless BIO_BLKG_REF
is already set. Use bio_blkg() in the BFQ and IOCOST merge paths which
may need to create a blkg, while keeping blk_cgroup_bio_start() and
completion paths lookup-only.
- Move CSS online-reference handling into
bio_associate_blkcg_from_css(), including fallback to the root blkcg, so
bio_associate_blkcg() does not take a redundant reference.
- Keep the v1 async bio punt conversion as patch 4 and document that
async_bio_lock protects async_bios.
Previous versions:
v1: https://lore.kernel.org/r/20260804065313.2092022-1-yukuai@kernel.org
Related series:
[1] RFC v2 blk-cgroup: protect blkgs with blkcg_mutex
https://lore.kernel.org/r/20260724123037.3004560-1-yukuai@kernel.org
Yu Kuai (4):
blk-cgroup: wait for old blkgs to leave queue before disk rebind
blk-cgroup: use a request_queue rhashtable for blkg lookup
blk-cgroup: store blkcg in bio instead of blkg
blk-cgroup: move async bio punt state to blkcg
Documentation/admin-guide/cgroup-v2.rst | 2 +-
block/bfq-cgroup.c | 16 +-
block/bfq-iosched.c | 19 +-
block/bio.c | 22 +-
block/blk-cgroup-fc-appid.c | 10 +-
block/blk-cgroup.c | 348 ++++++++++++++----------
block/blk-cgroup.h | 82 ++++--
block/blk-core.c | 9 +-
block/blk-crypto-fallback.c | 2 +-
block/blk-iocost.c | 12 +-
block/blk-iolatency.c | 11 +-
block/blk-ioprio.c | 2 +-
block/blk-throttle.c | 2 +-
block/blk-throttle.h | 2 +-
drivers/md/bcache/request.c | 2 +-
drivers/md/dm.c | 2 +-
drivers/md/md.c | 2 +-
drivers/nvdimm/nd_virtio.c | 2 +-
fs/gfs2/lops.c | 3 +-
include/linux/bio.h | 26 +-
include/linux/blk_types.h | 9 +-
include/linux/blkdev.h | 2 +
include/linux/writeback.h | 2 +-
mm/page_io.c | 13 +-
24 files changed, 357 insertions(+), 245 deletions(-)
base-commit: f2690679ecf3a3151688ebef766dd2512ff95854
--
2.51.0
What tree does this apply to? I get failures both for Jens' for-7.3/block and for-next trees in bfq-cgroups.c and bio.c On Tue, Aug 11, 2026 at 02:47:40PM +0800, Yu Kuai wrote: > From: Yu Kuai <yukuai@fygo.io> > > This RFC remains a preparatory series for the blkcg_mutex conversion > proposed in the related blkcg_mutex RFC v2 series [1]. That conversion > moves queue-local blkg topology synchronization from q->queue_lock to > q->blkcg_mutex, which is awkward while bios directly store queue-local > blkg references. > > v1 made the stored bio association queue-independent by replacing bi_blkg > with bi_blkcg, but a bio-owned blkg reference still had to be recovered by > looking up the bio's blkcg and current request_queue. Tao Cui reported that > cgroup removal deletes a dying blkg from the per-blkcg radix tree before a > throttled bio drops its reference. A later lookup for that pinned blkg then > fails, triggers the warning in bio_pinned_blkg(), and leaks the reference. > > v2 makes request_queue the authoritative lookup owner before converting the > bio association. A queue-owned rhashtable, keyed by the blkcg CSS ID, keeps > dying blkgs discoverable until their references drain while q->blkg_list > remains available for ordered walks. The bio conversion then stores and > pins the blkcg CSS, lazily creates a blkg only for users which need one, and > uses lookup-only access for completion and accounting paths which already > own a blkg reference. Async bio punt state is finally moved from blkg to > blkcg so punting alone does not instantiate a queue-local blkg. > > Changes since v1: > > - Add patch 1 to wait for every old blkg to leave q->blkg_list before a > shared request_queue is rebound, instead of treating root_blkg == NULL > as completion of asynchronous blkg teardown. > - Add patch 2 to replace the per-blkcg radix tree and lookup hint with a > request_queue rhashtable keyed by blkcg->css.id, as suggested by > Christoph Hellwig. Keep dying pinned blkgs in the hash until > blkg_release() so bio-owned references remain discoverable. > - Fold the v1 helper-only patch into patch 3, as suggested by Jan Kara and > Christoph Hellwig, and make bio_blkcg() naturally return NULL for an > unassociated bio. > - Rework patch 3 so blkg_lookup_create() acquires the bio-owned reference, > falls back to a live parent when creation or tryget fails, and updates > bi_blkcg when the returned blkg belongs to an ancestor. > - Make bio_blkg_lookup() lookup-only: it returns NULL unless BIO_BLKG_REF > is already set. Use bio_blkg() in the BFQ and IOCOST merge paths which > may need to create a blkg, while keeping blk_cgroup_bio_start() and > completion paths lookup-only. > - Move CSS online-reference handling into > bio_associate_blkcg_from_css(), including fallback to the root blkcg, so > bio_associate_blkcg() does not take a redundant reference. > - Keep the v1 async bio punt conversion as patch 4 and document that > async_bio_lock protects async_bios. > > Previous versions: > v1: https://lore.kernel.org/r/20260804065313.2092022-1-yukuai@kernel.org > > Related series: > [1] RFC v2 blk-cgroup: protect blkgs with blkcg_mutex > https://lore.kernel.org/r/20260724123037.3004560-1-yukuai@kernel.org > > Yu Kuai (4): > blk-cgroup: wait for old blkgs to leave queue before disk rebind > blk-cgroup: use a request_queue rhashtable for blkg lookup > blk-cgroup: store blkcg in bio instead of blkg > blk-cgroup: move async bio punt state to blkcg > > Documentation/admin-guide/cgroup-v2.rst | 2 +- > block/bfq-cgroup.c | 16 +- > block/bfq-iosched.c | 19 +- > block/bio.c | 22 +- > block/blk-cgroup-fc-appid.c | 10 +- > block/blk-cgroup.c | 348 ++++++++++++++---------- > block/blk-cgroup.h | 82 ++++-- > block/blk-core.c | 9 +- > block/blk-crypto-fallback.c | 2 +- > block/blk-iocost.c | 12 +- > block/blk-iolatency.c | 11 +- > block/blk-ioprio.c | 2 +- > block/blk-throttle.c | 2 +- > block/blk-throttle.h | 2 +- > drivers/md/bcache/request.c | 2 +- > drivers/md/dm.c | 2 +- > drivers/md/md.c | 2 +- > drivers/nvdimm/nd_virtio.c | 2 +- > fs/gfs2/lops.c | 3 +- > include/linux/bio.h | 26 +- > include/linux/blk_types.h | 9 +- > include/linux/blkdev.h | 2 + > include/linux/writeback.h | 2 +- > mm/page_io.c | 13 +- > 24 files changed, 357 insertions(+), 245 deletions(-) > > > base-commit: f2690679ecf3a3151688ebef766dd2512ff95854 > -- > 2.51.0 ---end quoted text---
Hi, 在 2026/8/14 14:45, Christoph Hellwig 写道: > What tree does this apply to? I get failures both for Jens' > for-7.3/block and for-next trees in bfq-cgroups.c and bio.c Oh, just realize this set is cooked based on Jens' initial for-7.3/block branch. With the other set that is already applied: 30d0c34b72f8 (HEAD -> block-7.3-blkg_list-rhashtable) blk-cgroup: move async bio punt state to blkcg 1aa13cdcc027 blk-cgroup: store blkcg in bio instead of blkg 058ff5f9c8ac blk-cgroup: use a request_queue rhashtable for blkg lookup fefb6604e496 blk-cgroup: wait for old blkgs to leave queue before disk rebind f2690679ecf3 (for-7.3/block) blk-cgroup: factor policy pd teardown loop into helper ed3105cce735 blk-cgroup: skip dying blkg in blkcg_activate_policy() 415bd622f1a3 blk-cgroup: fix race between policy activation and blkg destruction 4cc0299aea5d blk-cgroup: protect q->blkg_list iteration in blkg_destroy_all() with blkcg_mutex f5098b6bae76 (tag: v7.2-rc5, block-7.2) Linux 7.2-rc5 I'll rebase to the latest for-7.3/block branch in the next version. > > On Tue, Aug 11, 2026 at 02:47:40PM +0800, Yu Kuai wrote: >> From: Yu Kuai <yukuai@fygo.io> >> >> This RFC remains a preparatory series for the blkcg_mutex conversion >> proposed in the related blkcg_mutex RFC v2 series [1]. That conversion >> moves queue-local blkg topology synchronization from q->queue_lock to >> q->blkcg_mutex, which is awkward while bios directly store queue-local >> blkg references. >> >> v1 made the stored bio association queue-independent by replacing bi_blkg >> with bi_blkcg, but a bio-owned blkg reference still had to be recovered by >> looking up the bio's blkcg and current request_queue. Tao Cui reported that >> cgroup removal deletes a dying blkg from the per-blkcg radix tree before a >> throttled bio drops its reference. A later lookup for that pinned blkg then >> fails, triggers the warning in bio_pinned_blkg(), and leaks the reference. >> >> v2 makes request_queue the authoritative lookup owner before converting the >> bio association. A queue-owned rhashtable, keyed by the blkcg CSS ID, keeps >> dying blkgs discoverable until their references drain while q->blkg_list >> remains available for ordered walks. The bio conversion then stores and >> pins the blkcg CSS, lazily creates a blkg only for users which need one, and >> uses lookup-only access for completion and accounting paths which already >> own a blkg reference. Async bio punt state is finally moved from blkg to >> blkcg so punting alone does not instantiate a queue-local blkg. >> >> Changes since v1: >> >> - Add patch 1 to wait for every old blkg to leave q->blkg_list before a >> shared request_queue is rebound, instead of treating root_blkg == NULL >> as completion of asynchronous blkg teardown. >> - Add patch 2 to replace the per-blkcg radix tree and lookup hint with a >> request_queue rhashtable keyed by blkcg->css.id, as suggested by >> Christoph Hellwig. Keep dying pinned blkgs in the hash until >> blkg_release() so bio-owned references remain discoverable. >> - Fold the v1 helper-only patch into patch 3, as suggested by Jan Kara and >> Christoph Hellwig, and make bio_blkcg() naturally return NULL for an >> unassociated bio. >> - Rework patch 3 so blkg_lookup_create() acquires the bio-owned reference, >> falls back to a live parent when creation or tryget fails, and updates >> bi_blkcg when the returned blkg belongs to an ancestor. >> - Make bio_blkg_lookup() lookup-only: it returns NULL unless BIO_BLKG_REF >> is already set. Use bio_blkg() in the BFQ and IOCOST merge paths which >> may need to create a blkg, while keeping blk_cgroup_bio_start() and >> completion paths lookup-only. >> - Move CSS online-reference handling into >> bio_associate_blkcg_from_css(), including fallback to the root blkcg, so >> bio_associate_blkcg() does not take a redundant reference. >> - Keep the v1 async bio punt conversion as patch 4 and document that >> async_bio_lock protects async_bios. >> >> Previous versions: >> v1: https://lore.kernel.org/r/20260804065313.2092022-1-yukuai@kernel.org >> >> Related series: >> [1] RFC v2 blk-cgroup: protect blkgs with blkcg_mutex >> https://lore.kernel.org/r/20260724123037.3004560-1-yukuai@kernel.org >> >> Yu Kuai (4): >> blk-cgroup: wait for old blkgs to leave queue before disk rebind >> blk-cgroup: use a request_queue rhashtable for blkg lookup >> blk-cgroup: store blkcg in bio instead of blkg >> blk-cgroup: move async bio punt state to blkcg >> >> Documentation/admin-guide/cgroup-v2.rst | 2 +- >> block/bfq-cgroup.c | 16 +- >> block/bfq-iosched.c | 19 +- >> block/bio.c | 22 +- >> block/blk-cgroup-fc-appid.c | 10 +- >> block/blk-cgroup.c | 348 ++++++++++++++---------- >> block/blk-cgroup.h | 82 ++++-- >> block/blk-core.c | 9 +- >> block/blk-crypto-fallback.c | 2 +- >> block/blk-iocost.c | 12 +- >> block/blk-iolatency.c | 11 +- >> block/blk-ioprio.c | 2 +- >> block/blk-throttle.c | 2 +- >> block/blk-throttle.h | 2 +- >> drivers/md/bcache/request.c | 2 +- >> drivers/md/dm.c | 2 +- >> drivers/md/md.c | 2 +- >> drivers/nvdimm/nd_virtio.c | 2 +- >> fs/gfs2/lops.c | 3 +- >> include/linux/bio.h | 26 +- >> include/linux/blk_types.h | 9 +- >> include/linux/blkdev.h | 2 + >> include/linux/writeback.h | 2 +- >> mm/page_io.c | 13 +- >> 24 files changed, 357 insertions(+), 245 deletions(-) >> >> >> base-commit: f2690679ecf3a3151688ebef766dd2512ff95854 >> -- >> 2.51.0 > ---end quoted text--- > -- Thanks, Kuai
On Fri, Aug 14, 2026 at 03:53:44PM +0800, yu kuai wrote: > I'll rebase to the latest for-7.3/block branch in the next version. Thanks. For anything complicated a link to the git branch can also be helpful.
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