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| author |  Waiman Long <longman@redhat.com>
| 2022-11-04 20:59:02 -0400 |
|---|---|---|
| committer |  Jens Axboe <axboe@kernel.dk>
| 2022-11-16 16:58:44 -0700 |
| commit | dae590a6c96c799434e0ff8156ef29b88c257e60 (patch) | |
| tree | 47cc80856cb5e7b653e9ba8a70899b04c83ed850 /include | |
| parent | blk-cgroup: Optimize blkcg_rstat_flush() (diff) | |
| download | linux-dae590a6c96c799434e0ff8156ef29b88c257e60.tar.gz linux-dae590a6c96c799434e0ff8156ef29b88c257e60.tar.bz2 linux-dae590a6c96c799434e0ff8156ef29b88c257e60.zip | |
blk-cgroup: Flush stats at blkgs destruction path
As noted by Michal, the blkg_iostat_set's in the lockless list
hold reference to blkg's to protect against their removal. Those
blkg's hold reference to blkcg. When a cgroup is being destroyed,
cgroup_rstat_flush() is only called at css_release_work_fn() which is
called when the blkcg reference count reaches 0. This circular dependency
will prevent blkcg from being freed until some other events cause
cgroup_rstat_flush() to be called to flush out the pending blkcg stats.
To prevent this delayed blkcg removal, add a new cgroup_rstat_css_flush()
function to flush stats for a given css and cpu and call it at the blkgs
destruction path, blkcg_destroy_blkgs(), whenever there are still some
pending stats to be flushed. This will ensure that blkcg reference
count can reach 0 ASAP.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20221105005902.407297-4-longman@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cgroup.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 528bd44b59e2..6c4e66b3fa84 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -766,6 +766,7 @@ void cgroup_rstat_flush(struct cgroup *cgrp); void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp); void cgroup_rstat_flush_hold(struct cgroup *cgrp); void cgroup_rstat_flush_release(void); +void cgroup_rstat_css_cpu_flush(struct cgroup_subsys_state *css, int cpu); /* * Basic resource stats. |