Messages in this thread | | | Date | Mon, 16 Nov 2015 10:59:11 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH cgroup/for-4.4-fixes] cgroup: fix cftype->file_offset handling |
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On Thu, Nov 05, 2015 at 12:12:24AM -0500, Tejun Heo wrote: > 6f60eade2433 ("cgroup: generalize obtaining the handles of and > notifying cgroup files") introduced cftype->file_offset so that the > handles for per-css file instances can be recorded. These handles > then can be used, for example, to generate file modified > notifications. > > Unfortunately, it made the wrong assumption that files are created > once for a given css and removed on its destruction. Due to the > dependencies among subsystems, a css may be hidden from userland and > then later shown again. This is implemented by removing and > re-creating the affected files, so the associated kernfs_node for a > given cgroup file may change over time. This incorrect assumption led > to the corruption of css->files lists. > > Reimplement cftype->file_offset handling so that cgroup_file->kn is > protected by a lock and updated as files are created and destroyed. > This also makes keeping them on per-cgroup list unnecessary.
Applied to cgroup/for-4.4-fixes.
-- tejun
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