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| author | Tejun Heo <tj@kernel.org> | 2024-06-26 04:29:58 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-07-04 16:59:52 +0300 |
| commit | d329605287020c3d1c3b0dadc63d8208e7251382 (patch) | |
| tree | 8e96bade108c8790c2f317621c616c085ad62c83 /kernel/sched/core.c | |
| parent | 0ec208ce9834929769ace0e2a506106192d08069 (diff) | |
| download | linux-d329605287020c3d1c3b0dadc63d8208e7251382.tar.xz | |
sched/fair: set_load_weight() must also call reweight_task() for SCHED_IDLE tasks
When a task's weight is being changed, set_load_weight() is called with
@update_load set. As weight changes aren't trivial for the fair class,
set_load_weight() calls fair.c::reweight_task() for fair class tasks.
However, set_load_weight() first tests task_has_idle_policy() on entry and
skips calling reweight_task() for SCHED_IDLE tasks. This is buggy as
SCHED_IDLE tasks are just fair tasks with a very low weight and they would
incorrectly skip load, vlag and position updates.
Fix it by updating reweight_task() to take struct load_weight as idle weight
can't be expressed with prio and making set_load_weight() call
reweight_task() for SCHED_IDLE tasks too when @update_load is set.
Fixes: 9059393e4ec1 ("sched/fair: Use reweight_entity() for set_user_nice()")
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org # v4.15+
Link: http://lkml.kernel.org/r/20240624102331.GI31592@noisy.programming.kicks-ass.net
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0935f9d4bb7b..747683487be7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1328,27 +1328,24 @@ int tg_nop(struct task_group *tg, void *data) void set_load_weight(struct task_struct *p, bool update_load) { int prio = p->static_prio - MAX_RT_PRIO; - struct load_weight *load = &p->se.load; + struct load_weight lw; - /* - * SCHED_IDLE tasks get minimal weight: - */ if (task_has_idle_policy(p)) { - load->weight = scale_load(WEIGHT_IDLEPRIO); - load->inv_weight = WMULT_IDLEPRIO; - return; + lw.weight = scale_load(WEIGHT_IDLEPRIO); + lw.inv_weight = WMULT_IDLEPRIO; + } else { + lw.weight = scale_load(sched_prio_to_weight[prio]); + lw.inv_weight = sched_prio_to_wmult[prio]; } /* * SCHED_OTHER tasks have to update their load when changing their * weight */ - if (update_load && p->sched_class == &fair_sched_class) { - reweight_task(p, prio); - } else { - load->weight = scale_load(sched_prio_to_weight[prio]); - load->inv_weight = sched_prio_to_wmult[prio]; - } + if (update_load && p->sched_class == &fair_sched_class) + reweight_task(p, &lw); + else + p->se.load = lw; } #ifdef CONFIG_UCLAMP_TASK |