The origin bio carries blk-cgroup information which could be set from
foreground(task_css(css) - wbc->wb->blkcg_css), so the blkcg won't
control buffer io since commit ca522482e3eaf ("dm: pass NULL bdev to
bio_alloc_clone"). The synchronous io is still under control by blkcg,
because 'bio->bi_blkg' is set by io submitting task which has been
added into 'cgroup.procs'.Fix it by passing origin bio's bdev to bio_alloc_clone. Fetch a reproducer in [Link]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=220985 Fixes: ca522482e3eaf ("dm: pass NULL bdev to bio_alloc_clone") Signed-off-by: Zhihao Cheng <[email protected]> --- drivers/md/dm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index b63279202260..e763e3b02a9f 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -574,7 +574,8 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio, gfp_t g struct dm_target_io *tio; struct bio *clone; - clone = bio_alloc_clone(NULL, bio, gfp_mask, &md->mempools->io_bs); + clone = bio_alloc_clone(bio->bi_bdev, bio, + gfp_mask, &md->mempools->io_bs); if (unlikely(!clone)) return NULL; tio = clone_to_tio(clone); @@ -623,7 +624,7 @@ static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti, /* alloc_io() already initialized embedded clone */ clone = &tio->clone; } else { - clone = bio_alloc_clone(NULL, ci->bio, gfp_mask, + clone = bio_alloc_clone(ci->bio->bi_bdev, ci->bio, gfp_mask, &md->mempools->bs); if (!clone) return NULL; -- 2.52.0
