From 3dd95f077371f5def65a91c4bb13bd574a62bc3a Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Fri, 7 Aug 2026 03:52:08 +0000 Subject: [PATCH] sched/core: Don't steal a proxy-exec donor try_steal_cookie() avoids stealing src->core_pick and src->curr before moving a task with the same cookie via move_queued_task_locked(). With proxy-exec, src->donor is the current scheduling context and may differ from src->curr. Stealing it migrates a task that the source rq still treats as current, leaving src's scheduler state for that task stale. For CFS this means cfs_rq->curr points at the stolen entity, and the next pick on the source rq hits the WARN_ON_ONCE in put_prev_entity(). Commit 7de9d4f94638 ("sched: Start blocked_on chain processing in find_proxy_task()") tweaked the fair class logic so that the donor task isn't migrated away while we're running the proxy. Do it similarly for try_steal_cookie() and skip src->donor as well. Fixes: 7de9d4f94638 ("sched: Start blocked_on chain processing in find_proxy_task()") Signed-off-by: Vasily Gorbik Signed-off-by: John Stultz Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260807035232.1881495-3-jstultz@google.com --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 74724501c623..7adbdccc98c6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6509,7 +6509,7 @@ static bool try_steal_cookie(int this, int that) return false; do { - if (p == src->core_pick || p == src->curr) + if (p == src->core_pick || p == src->curr || p == src->donor) goto next; if (!is_cpu_allowed(p, this))