Modified to apply against https://gitlab.com/xanmod/linux/-/commit/40fc4fc51b847d47e11a53baa8844f69f01b3d86 From 127b90315ca07ccad2618db7ba950a63e3b32d22 Mon Sep 17 00:00:00 2001 From: Fernand Sieber Date: Thu, 6 Nov 2025 12:40:10 +0200 Subject: sched/proxy: Yield the donor task When executing a task in proxy context, handle yields as if they were requested by the donor task. This matches the traditional PI semantics of yield() as well. This avoids scenario like proxy task yielding, pick next task selecting the same previous blocked donor, running the proxy task again, etc. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202510211205.1e0f5223-lkp@intel.com Suggested-by: Peter Zijlstra Signed-off-by: Fernand Sieber Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251106104022.195157-1-sieberf@amazon.com --- kernel/sched/deadline.c | 2 +- kernel/sched/ext.c | 4 ++-- kernel/sched/fair.c | 2 +- kernel/sched/rt.c | 2 +- kernel/sched/syscalls.c | 5 +++-- 5 files changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 6b8a9286e2fca2..13112c680f9228 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2143,7 +2143,7 @@ static void yield_task_dl(struct rq *rq) * it and the bandwidth timer will wake it up and will give it * new scheduling parameters (thanks to dl_yielded=1). */ - rq->curr->dl.dl_yielded = 1; + rq->donor->dl.dl_yielded = 1; update_rq_clock(rq); update_curr_dl(rq); diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index b063444dc003f9..224b72c8e8da94 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -1474,7 +1474,7 @@ static bool dequeue_task_scx(struct rq *rq, struct task_struct *p, int deq_flags static void yield_task_scx(struct rq *rq) { struct scx_sched *sch = scx_root; - struct task_struct *p = rq->curr; + struct task_struct *p = rq->donor; if (SCX_HAS_OP(sch, yield)) SCX_CALL_OP_2TASKS_RET(sch, SCX_KF_REST, yield, rq, p, NULL); @@ -1485,7 +1485,7 @@ static void yield_task_scx(struct rq *rq) static bool yield_to_task_scx(struct rq *rq, struct task_struct *to) { struct scx_sched *sch = scx_root; - struct task_struct *from = rq->curr; + struct task_struct *from = rq->donor; if (SCX_HAS_OP(sch, yield)) return SCX_CALL_OP_2TASKS_RET(sch, SCX_KF_REST, yield, rq, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 273e2871b59e70..f1d8eb350f595f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8980,7 +8980,7 @@ static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, struct t */ static void yield_task_fair(struct rq *rq) { - struct task_struct *curr = rq->curr; + struct task_struct *curr = rq->donor; struct cfs_rq *cfs_rq = task_cfs_rq(curr); struct sched_entity *se = &curr->se; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 1fd97f2d7ec628..f1867fe8e5c535 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1490,7 +1490,7 @@ static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head) static void yield_task_rt(struct rq *rq) { - requeue_task_rt(rq, rq->curr, 0); + requeue_task_rt(rq, rq->donor, 0); } static int find_lowest_rq(struct task_struct *task); diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c index 8f0f603b530bef..807879131add85 100644 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -1319,9 +1319,9 @@ static void do_sched_yield(void) rq = this_rq_lock_irq(&rf); schedstat_inc(rq->yld_count); if (sysctl_sched_yield_type > 1) - current->sched_class->yield_task(rq); + rq->donor->sched_class->yield_task(rq); preempt_disable(); rq_unlock_irq(rq, &rf); @@ -1388,12 +1388,13 @@ EXPORT_SYMBOL(yield); */ int __sched yield_to(struct task_struct *p, bool preempt) { - struct task_struct *curr = current; + struct task_struct *curr; struct rq *rq, *p_rq; int yielded = 0; scoped_guard (raw_spinlock_irqsave, &p->pi_lock) { rq = this_rq(); + curr = rq->donor; again: p_rq = task_rq(p); -- cgit 1.2.3-korg