From dbbca20764382b4d411ec2918f4e278ffe547acc Mon Sep 17 00:00:00 2001 From: Tao Cui Date: Wed, 15 Jul 2026 21:24:07 +0800 Subject: [PATCH] blk-cgroup: fix leaks and online flag on radix_tree_insert failure MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. Fix by replacing blkg_put() with percpu_ref_kill(), matching the pattern used in blkg_destroy(). Acked-by: Tejun Heo Signed-off-by: Tao Cui Link: https://patch.msgid.link/20260715132407.1469777-1-cui.tao@linux.dev Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index d2a1f5903f24..d9676126c5b5 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -434,15 +434,15 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk, blkg->pd[i]->online = true; } } + blkg->online = true; } - blkg->online = true; spin_unlock(&blkcg->lock); if (!ret) return blkg; /* @blkg failed fully initialized, use the usual release path */ - blkg_put(blkg); + percpu_ref_kill(&blkg->refcnt); return ERR_PTR(ret); err_free_blkg: