Re: [RFC PATCH v1 6/9] freezer: Set default freeze priority for zombie tasks

On 08/11, Zihuan Zhang wrote:

在 2025/8/8 22:29, Oleg Nesterov 写道:

quoted

On 08/07, Zihuan Zhang wrote:

quoted

@@ -6980,6 +6981,7 @@ void __noreturn do_task_dead(void)
 	current->flags |= PF_NOFREEZE;

 	__schedule(SM_NONE);
+	freeze_set_default_priority(current, FREEZE_PRIORITY_NEVER);
 	BUG();

But this change has no effect?

Firstly, this last __schedule() should not return, note the BUG() we have.

Secondly, this zombie is already PF_NOFREEZE, freeze_task() will return
false anyway.

Sorry, but in our tests with a large number of zombie tasks, returning early
reduced the overhead. Even though freeze_task() would return false for
PF_NOFREEZE, skipping the extra path still saved time in our suspend/freezer

https://lore.kernel.org/all/20250707084214.GD1613200@noisy.programming.kicks-ass.net/ (local)

Anyway the patch makes no sense in its current form, see my note
about __schedule() above.

Oleg.