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charset=us-ascii Content-Disposition: inline In-Reply-To: <20260521025250.1469390-1-chenguanyou@xiaomi.com> X-Stat-Signature: e8ew44zspphfakt89611951o6e9zkmhf X-Rspamd-Queue-Id: 2D92C4000E X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1779347091-2135 X-HE-Meta: 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 nEAbmidK N1Q0X0w1T189p0DY+bXiEx8xiRUCVoeAD8zPUZ+KkyOVdJJIMj6CMLa+FkZ7C2Di3yEh9m0nu83CG2/l81TV3xv9SChARpenS5hWyTQX9SQLrpdssvsQyEXJBnPQQGJNThYQNQPX0f7oe+vpi9MFOmMIXSBhNjGnc5ezAK71x+KXfu3w20vkaM2AGW2ykxH52vwEi9Z/yi/lKGbLX2iC1A8d+vJ3UgKNol9+HAKoZo25uVlnidM+ZpYjZdF2qizr3J5zSdQE0sbq2KJUD0GGRf4/MpEeGxrYjPE9b2r5qP010RJumzlLwLxc4yMxMCDKcACbv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, May 21, 2026 at 10:52:50AM +0800, Guanyou.Chen wrote: > diff --git a/init/init_task.c b/init/init_task.c > index 5c838757fc10..57ff8dae9bfb 100644 > --- a/init/init_task.c > +++ b/init/init_task.c > @@ -170,6 +170,7 @@ struct task_struct init_task __aligned(L1_CACHE_BYTES) = { > INIT_CPU_TIMERS(init_task) > .pi_lock = __RAW_SPIN_LOCK_UNLOCKED(init_task.pi_lock), > .timer_slack_ns = 50000, /* 50 usec default slack */ > + .default_timer_slack_ns = 50000, /* 50 usec default slack */ > .thread_pid = &init_struct_pid, > .thread_node = LIST_HEAD_INIT(init_signals.thread_head), > #ifdef CONFIG_AUDIT > diff --git a/kernel/fork.c b/kernel/fork.c > index 65113a304518..8358df80e11d 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -2133,8 +2133,6 @@ __latent_entropy struct task_struct *copy_process( > retval = -EAGAIN; > #endif > > - p->default_timer_slack_ns = current->timer_slack_ns; > - > #ifdef CONFIG_PSI > p->psi_flags = 0; > #endif Cunlong makes a good point in that this changes behaviour. That said I do find the current behaviour 'odd'. *IF* we want to change this (and changing behaviour is always dodgy), then it should be a separate patch with a separate justification. > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index b7f77c165a6e..b1a241810ce0 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4649,6 +4649,7 @@ int sched_fork(u64 clone_flags, struct task_struct *p) > p->policy = SCHED_NORMAL; > p->static_prio = NICE_TO_PRIO(0); > p->rt_priority = 0; > + p->timer_slack_ns = p->default_timer_slack_ns; > } else if (PRIO_TO_NICE(p->static_prio) < 0) > p->static_prio = NICE_TO_PRIO(0); Yes, this matches __setscheduler_param(). And yes, this wants to be done. Anyway, while looking at all this I found that the manpages specify RESET_ON_FORK to apply to CAP_SYS properties; which is a tad awkward, esp if we end up allowing unpriv access to DL (or even FIFO/RR when isolated in a bandwidth group). Additionally, it doesn't look like PR_SET_TIMERSLACK is CAP_SYS guarded itself, so this is all a bit of a mess.