Re: [PATCH v4] blk-cgroup: fix leaks and online flag on radix_tree_insert failure

[Jens Axboe]

On Wed, 15 Jul 2026 21:24:07 +0800, Tao Cui wrote:
> When radix_tree_insert() fails in blkg_create(), the error path has two
> issues:
> 
> 1. blkg->online is set to true unconditionally, even when the blkg was
>    never fully inserted.  Move the assignment inside the success block.
> 
> 2. The error path calls blkg_put() without first calling
>    percpu_ref_kill().  Because the refcount is still in percpu mode,
>    percpu_ref_put() only does this_cpu_sub() without checking for zero,
>    so blkg_release() is never triggered.  This permanently leaks the
>    blkg memory, its percpu iostat, policy data, the parent blkg
>    reference, and the cgroup css reference — the latter preventing the
>    cgroup from ever being destroyed.
> 
> [...]

Applied, thanks!

[1/1] blk-cgroup: fix leaks and online flag on radix_tree_insert failure
      commit: dbbca20764382b4d411ec2918f4e278ffe547acc

Best regards,
-- 
Jens Axboe