diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2023-01-19 19:03:49 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-29 15:19:04 -0700 |
| commit | dfd6200a095440b663099d8d42f1efb0175a1ce3 (patch) | |
| tree | 5238b2ac06a92d833d47004866e27c2f2bc3346d /block/blk-cgroup.c | |
| parent | c7241babf0855d8a6180cd1743ff0ec34de40b4e (diff) | |
blk-cgroup: support to track if policy is online
A new field 'online' is added to blkg_policy_data to fix following
2 problem:
1) In blkcg_activate_policy(), if pd_alloc_fn() with 'GFP_NOWAIT'
failed, 'queue_lock' will be dropped and pd_alloc_fn() will try again
without 'GFP_NOWAIT'. In the meantime, remove cgroup can race with
it, and pd_offline_fn() will be called without pd_init_fn() and
pd_online_fn(). This way null-ptr-deference can be triggered.
2) In order to synchronize pd_free_fn() from blkg_free_workfn() and
blkcg_deactivate_policy(), 'list_del_init(&blkg->q_node)' will be
delayed to blkg_free_workfn(), hence pd_offline_fn() can be called
first in blkg_destroy(), and then blkcg_deactivate_policy() will
call it again, we must prevent it.
The new field 'online' will be set after pd_online_fn() and will be
cleared after pd_offline_fn(), in the meantime pd_offline_fn() will only
be called if 'online' is set.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230119110350.2287325-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-cgroup.c')
| -rw-r--r-- | block/blk-cgroup.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index c6d7d1fce65a..75f3c4460715 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -288,6 +288,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, blkg->pd[i] = pd; pd->blkg = blkg; pd->plid = i; + pd->online = false; } return blkg; @@ -359,8 +360,11 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk, for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; - if (blkg->pd[i] && pol->pd_online_fn) - pol->pd_online_fn(blkg->pd[i]); + if (blkg->pd[i]) { + if (pol->pd_online_fn) + pol->pd_online_fn(blkg->pd[i]); + blkg->pd[i]->online = true; + } } } blkg->online = true; @@ -465,8 +469,11 @@ static void blkg_destroy(struct blkcg_gq *blkg) for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; - if (blkg->pd[i] && pol->pd_offline_fn) - pol->pd_offline_fn(blkg->pd[i]); + if (blkg->pd[i] && blkg->pd[i]->online) { + if (pol->pd_offline_fn) + pol->pd_offline_fn(blkg->pd[i]); + blkg->pd[i]->online = false; + } } blkg->online = false; @@ -1448,6 +1455,7 @@ retry: blkg->pd[pol->plid] = pd; pd->blkg = blkg; pd->plid = pol->plid; + pd->online = false; } /* all allocated, init in the same order */ @@ -1455,9 +1463,11 @@ retry: list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) pol->pd_init_fn(blkg->pd[pol->plid]); - if (pol->pd_online_fn) - list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) + list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { + if (pol->pd_online_fn) pol->pd_online_fn(blkg->pd[pol->plid]); + blkg->pd[pol->plid]->online = true; + } __set_bit(pol->plid, q->blkcg_pols); ret = 0; @@ -1519,7 +1529,7 @@ void blkcg_deactivate_policy(struct request_queue *q, spin_lock(&blkcg->lock); if (blkg->pd[pol->plid]) { - if (pol->pd_offline_fn) + if (blkg->pd[pol->plid]->online && pol->pd_offline_fn) pol->pd_offline_fn(blkg->pd[pol->plid]); pol->pd_free_fn(blkg->pd[pol->plid]); blkg->pd[pol->plid] = NULL; |