diff options
| author | Ming Lei <ming.lei@redhat.com> | 2026-03-11 11:28:37 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-03-11 08:30:30 -0600 |
| commit | 3dbaacf6ab68f81e3375fe769a2ecdbd3ce386fd (patch) | |
| tree | f5b83097242860abc02d0c5b6dcbdd84b6a7cc36 | |
| parent | daa6c79858e9ca75c548452bf71db8a9e61bde42 (diff) | |
blk-cgroup: wait for blkcg cleanup before initializing new disk
When a queue is shared across disk rebind (e.g., SCSI unbind/bind), the
previous disk's blkcg state is cleaned up asynchronously via
disk_release() -> blkcg_exit_disk(). If the new disk's blkcg_init_disk()
runs before that cleanup finishes, we may overwrite q->root_blkg while
the old one is still alive, and radix_tree_insert() in blkg_create()
fails with -EEXIST because the old blkg entries still occupy the same
queue id slot in blkcg->blkg_tree. This causes the sd probe to fail
with -ENOMEM.
Fix it by waiting in blkcg_init_disk() for root_blkg to become NULL,
which indicates the previous disk's blkcg cleanup has completed.
Fixes: 1059699f87eb ("block: move blkcg initialization/destroy into disk allocation/release handler")
Cc: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260311032837.2368714-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-cgroup.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index b70096497d38..2d7b18eb7291 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -24,6 +24,7 @@ #include <linux/backing-dev.h> #include <linux/slab.h> #include <linux/delay.h> +#include <linux/wait_bit.h> #include <linux/atomic.h> #include <linux/ctype.h> #include <linux/resume_user_mode.h> @@ -611,6 +612,8 @@ restart: q->root_blkg = NULL; spin_unlock_irq(&q->queue_lock); + + wake_up_var(&q->root_blkg); } static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) @@ -1498,6 +1501,18 @@ int blkcg_init_disk(struct gendisk *disk) struct blkcg_gq *new_blkg, *blkg; bool preloaded; + /* + * If the queue is shared across disk rebind (e.g., SCSI), the + * previous disk's blkcg state is cleaned up asynchronously via + * disk_release() -> blkcg_exit_disk(). Wait for that cleanup to + * finish (indicated by root_blkg becoming NULL) before setting up + * new blkcg state. Otherwise, we may overwrite q->root_blkg while + * the old one is still alive, and radix_tree_insert() in + * blkg_create() will fail with -EEXIST because the old entries + * still occupy the same queue id slot in blkcg->blkg_tree. + */ + wait_var_event(&q->root_blkg, !READ_ONCE(q->root_blkg)); + new_blkg = blkg_alloc(&blkcg_root, disk, GFP_KERNEL); if (!new_blkg) return -ENOMEM; |