On Fri, Jan 17, 2020 at 9:28 AM Tejun Heo tj@kernel.org wrote:
On Fri, Jan 17, 2020 at 04:15:32PM +0100, Michal Koutný wrote:
PF_EXITING is set earlier than actual removal from css_set when a task is exitting. This can confuse cgroup.procs readers who see no PF_EXITING tasks, however, rmdir is checking against css_set membership so it can transitionally fail with EBUSY.
Fix this by listing tasks that weren't unlinked from css_set active lists. It may happen that other users of the task iterator (without CSS_TASK_ITER_PROCS) spot a PF_EXITING task before cgroup_exit(). This is equal to the state before commit c03cd7738a83 ("cgroup: Include dying leaders with live threads in PROCS iterations") but it may be reviewed later.
Tested-by: Suren Baghdasaryan surenb@google.com
Yeah, this looks fine to me. Any chance you can order this before the clean up so that we can mark it for -stable.
+1 for reordering. Makes it easier to backport. Thanks, Suren.
Thanks.
-- tejun
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