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| author | Yu Kuai <yukuai3@huawei.com> | 2023-01-19 12:03:49 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-29 23:19:04 +0100 |
| commit | dfd6200a095440b663099d8d42f1efb0175a1ce3 (patch) | |
| tree | 5238b2ac06a92d833d47004866e27c2f2bc3346d /block/blk-cgroup.h | |
| parent | blk-cgroup: dropping parent refcount after pd_free_fn() is done (diff) | |
| download | linux-dfd6200a095440b663099d8d42f1efb0175a1ce3.tar.xz linux-dfd6200a095440b663099d8d42f1efb0175a1ce3.zip | |
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.h')
| -rw-r--r-- | block/blk-cgroup.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 1e94e404eaa8..b13ee84f358e 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -135,6 +135,7 @@ struct blkg_policy_data { /* the blkg and policy id this per-policy data belongs to */ struct blkcg_gq *blkg; int plid; + bool online; }; /* |