Friendly ping ...
Hope we can consider this for 7.1-rc1 merge window.
在 2026/3/4 15:38, Yu Kuai 写道:
> This series fixes several race conditions related to q->blkg_list iteration
> and improves the locking around blkcg policy activation/deactivation.
>
> Patch 1-2: Protect q->blkg_list iteration with blkcg_mutex in blkg_destroy_all()
> and bfq_end_wr_async() to prevent races with blkg_free_workfn().
>
> Patch 3-4: Fix use-after-free and memory leak issues in blkcg_activate_policy()
> by extending blkcg_mutex coverage and skipping dying blkgs.
>
> Patch 5: Refactor policy pd teardown into a helper function.
>
> Patch 6: Restructure blkcg_activate_policy() to allocate pds before freezing
> the queue, avoiding potential deadlocks from percpu allocation. Also fix
> locking order in blkcg_deactivate_policy() to be consistent with
> blkcg_activate_policy() (mutex -> freeze).
>
> Patch 7: Move rq_qos_mutex handling inside rq_qos_add()/rq_qos_del() to
> simplify the locking and eliminate potential deadlocks.
>
> Note: queue_lock is still used in many places to protect queue blkg.
> Future work is to convert it to blkcg_mutex entirely.
>
> Changes v2 -> v3:
> - Patch 2: Wrap mutex_lock/unlock with #ifdef CONFIG_BFQ_GROUP_IOSCHED to
> fix compile error when CONFIG_BLK_CGROUP is disabled.
> - Patch 6: Fix locking order in blkcg_deactivate_policy() to match
> blkcg_activate_policy() (mutex -> freeze instead of freeze -> mutex).
> - Patch 7: Remove stale lockdep_assert_held() in iolatency_set_limit().
>
> Changes v1 -> v2:
> - Link: https://lore.kernel.org/all/20260108014416.3656493-1-zhengqixing@huaweicloud.com/
>
> Yu Kuai (4):
> blk-cgroup: protect q->blkg_list iteration in blkg_destroy_all() with
> blkcg_mutex
> bfq: protect q->blkg_list iteration in bfq_end_wr_async() with
> blkcg_mutex
> blk-cgroup: allocate pds before freezing queue in
> blkcg_activate_policy()
> blk-rq-qos: move rq_qos_mutex acquisition inside rq_qos_add/del
>
> Zheng Qixing (3):
> blk-cgroup: fix race between policy activation and blkg destruction
> blk-cgroup: skip dying blkg in blkcg_activate_policy()
> blk-cgroup: factor policy pd teardown loop into helper
>
> block/bfq-cgroup.c | 3 +-
> block/bfq-iosched.c | 6 ++
> block/blk-cgroup.c | 205 ++++++++++++++----------------------------
> block/blk-cgroup.h | 2 -
> block/blk-iocost.c | 11 +--
> block/blk-iolatency.c | 5 --
> block/blk-rq-qos.c | 31 ++++---
> block/blk-wbt.c | 2 -
> 8 files changed, 97 insertions(+), 168 deletions(-)
>
--
Thansk,
Kuai