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| author | Yicong Yang <[email protected]> | 2025-06-27 03:54:20 +0000 |
|---|---|---|
| committer | Peter Zijlstra <[email protected]> | 2025-08-26 08:46:01 +0000 |
| commit | 52d15521eb75f9b521744db675bee61025d2fa52 (patch) | |
| tree | 621231d5c8d3069e9601d6eb461abaeaed18fae5 /lib/net_utils.c | |
| parent | sched/deadline: Fix RT task potential starvation when expiry time passed (diff) | |
| download | kernel-52d15521eb75f9b521744db675bee61025d2fa52.tar.gz kernel-52d15521eb75f9b521744db675bee61025d2fa52.zip | |
sched/deadline: Don't count nr_running for dl_server proxy tasks
On CPU offline the kernel stalled with below call trace:
INFO: task kworker/0:1:11 blocked for more than 120 seconds.
cpuhp hold the cpu hotplug lock endless and stalled vmstat_shepherd.
This is because we count nr_running twice on cpuhp enqueuing and failed
the wait condition of cpuhp:
enqueue_task_fair() // pick cpuhp from idle, rq->nr_running = 0
dl_server_start()
[...]
add_nr_running() // rq->nr_running = 1
add_nr_running() // rq->nr_running = 2
[switch to cpuhp, waiting on balance_hotplug_wait()]
rcuwait_wait_event(rq->nr_running == 1 && ...) // failed, rq->nr_running=2
schedule() // wait again
It doesn't make sense to count the dl_server towards runnable tasks,
since it runs other tasks.
Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Yicong Yang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Diffstat (limited to 'lib/net_utils.c')
0 files changed, 0 insertions, 0 deletions