Messages in this thread Patch in this message | | | Date | Wed, 7 Jul 2021 14:49:38 +0200 | From | Vasily Gorbik <> | Subject | [RFC PATCH] livepatch: Kick idle cpu's tasks to perform transition |
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On an idle system with large amount of cpus it might happen that klp_update_patch_state() is not reached in do_idle() for a long periods of time. With debug messages enabled log is filled with: [ 499.442643] livepatch: klp_try_switch_task: swapper/63:0 is running
without any signs of progress. Ending up with "failed to complete transition".
On s390 LPAR with 128 cpus not a single transition is able to complete and livepatch kselftests fail.
To deal with that, make sure we break out of do_idle() inner loop to reach klp_update_patch_state() by marking idle tasks as NEED_RESCHED as well as kick cpus out of idle state.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> --- kernel/livepatch/transition.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 3a4beb9395c4..793eba46e970 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -415,8 +415,11 @@ void klp_try_complete_transition(void) for_each_possible_cpu(cpu) { task = idle_task(cpu); if (cpu_online(cpu)) { - if (!klp_try_switch_task(task)) + if (!klp_try_switch_task(task)) { complete = false; + set_tsk_need_resched(task); + kick_process(task); + } } else if (task->patch_state != klp_target_state) { /* offline idle tasks can be switched immediately */ clear_tsk_thread_flag(task, TIF_PATCH_PENDING); -- 2.25.4
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