commit: 2fcc7a615b8b2de79d0b1b3ce13cb5430b8c80d4 Author: Mike Pagano <mpagano <AT> gentoo <DOT> org> AuthorDate: Thu Dec 5 20:05:18 2024 +0000 Commit: Mike Pagano <mpagano <AT> gentoo <DOT> org> CommitDate: Thu Dec 5 20:05:18 2024 +0000 URL: https://gitweb.gentoo.org/proj/linux-patches.git/commit/?id=2fcc7a61
sched: Initialize idle tasks only once Signed-off-by: Mike Pagano <mpagano <AT> gentoo.org> 0000_README | 4 ++ 1800_sched-init-idle-tasks-only-once.patch | 80 ++++++++++++++++++++++++++++++ 2 files changed, 84 insertions(+) diff --git a/0000_README b/0000_README index ac1104a1..f7334645 100644 --- a/0000_README +++ b/0000_README @@ -63,6 +63,10 @@ Patch: 1730_parisc-Disable-prctl.patch From: https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git Desc: prctl: Temporarily disable prctl(PR_SET_MDWE) on parisc +Patch: 1800_sched-init-idle-tasks-only-once.patch +From: https://git.kernel.org/ +Desc: sched: Initialize idle tasks only once + Patch: 2000_BT-Check-key-sizes-only-if-Secure-Simple-Pairing-enabled.patch From: https://lore.kernel.org/linux-bluetooth/[email protected]/raw Desc: Bluetooth: Check key sizes only when Secure Simple Pairing is enabled. See bug #686758 diff --git a/1800_sched-init-idle-tasks-only-once.patch b/1800_sched-init-idle-tasks-only-once.patch new file mode 100644 index 00000000..013a45fc --- /dev/null +++ b/1800_sched-init-idle-tasks-only-once.patch @@ -0,0 +1,80 @@ +From b23decf8ac9102fc52c4de5196f4dc0a5f3eb80b Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <[email protected]> +Date: Mon, 28 Oct 2024 11:43:42 +0100 +Subject: sched: Initialize idle tasks only once + +Idle tasks are initialized via __sched_fork() twice: + + fork_idle() + copy_process() + sched_fork() + __sched_fork() + init_idle() + __sched_fork() + +Instead of cleaning this up, sched_ext hacked around it. Even when analyis +and solution were provided in a discussion, nobody cared to clean this up. + +init_idle() is also invoked from sched_init() to initialize the boot CPU's +idle task, which requires the __sched_fork() invocation. But this can be +trivially solved by invoking __sched_fork() before init_idle() in +sched_init() and removing the __sched_fork() invocation from init_idle(). + +Do so and clean up the comments explaining this historical leftover. + +Signed-off-by: Thomas Gleixner <[email protected]> +Signed-off-by: Peter Zijlstra (Intel) <[email protected]> +Link: https://lore.kernel.org/r/[email protected] +--- + kernel/sched/core.c | 12 +++++------- + 1 file changed, 5 insertions(+), 7 deletions(-) + +(limited to 'kernel/sched/core.c') + +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index c57a79e3491103..aad48850c1ef0d 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -4423,7 +4423,8 @@ int wake_up_state(struct task_struct *p, unsigned int state) + * Perform scheduler related setup for a newly forked process p. + * p is forked by current. + * +- * __sched_fork() is basic setup used by init_idle() too: ++ * __sched_fork() is basic setup which is also used by sched_init() to ++ * initialize the boot CPU's idle task. + */ + static void __sched_fork(unsigned long clone_flags, struct task_struct *p) + { +@@ -7697,8 +7698,6 @@ void __init init_idle(struct task_struct *idle, int cpu) + struct rq *rq = cpu_rq(cpu); + unsigned long flags; + +- __sched_fork(0, idle); +- + raw_spin_lock_irqsave(&idle->pi_lock, flags); + raw_spin_rq_lock(rq); + +@@ -7713,10 +7712,8 @@ void __init init_idle(struct task_struct *idle, int cpu) + + #ifdef CONFIG_SMP + /* +- * It's possible that init_idle() gets called multiple times on a task, +- * in that case do_set_cpus_allowed() will not do the right thing. +- * +- * And since this is boot we can forgo the serialization. ++ * No validation and serialization required at boot time and for ++ * setting up the idle tasks of not yet online CPUs. + */ + set_cpus_allowed_common(idle, &ac); + #endif +@@ -8561,6 +8558,7 @@ void __init sched_init(void) + * but because we are the idle thread, we just pick up running again + * when this runqueue becomes "idle". + */ ++ __sched_fork(0, current); + init_idle(current, smp_processor_id()); + + calc_load_update = jiffies + LOAD_FREQ; +-- +cgit 1.2.3-korg +
