From: Juri Lelli <juri.lelli@redhat.com> stable inclusion from stable-v5.10.134 commit 26d5eb3c25c3b89bfd62f81f6afea71b350adaf2 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5ZVR7 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit ddfc710395cccc61247348df9eb18ea50321cbed upstream. Tasks the are being deboosted from SCHED_DEADLINE might enter enqueue_task_dl() one last time and hit an erroneous BUG_ON condition: since they are not boosted anymore, the if (is_dl_boosted()) branch is not taken, but the else if (!dl_prio) is and inside this one we BUG_ON(!is_dl_boosted), which is of course false (BUG_ON triggered) otherwise we had entered the if branch above. Long story short, the current condition doesn't make sense and always leads to triggering of a BUG. Fix this by only checking enqueue flags, properly: ENQUEUE_REPLENISH has to be present, but additional flags are not a problem. Fixes: 64be6f1f5f71 ("sched/deadline: Don't replenish from a !SCHED_DEADLINE entity") Signed-off-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20220714151908.533052-1-juri.lelli@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- kernel/sched/deadline.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index cb487d7d33e1..a6b69fae752e 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1563,7 +1563,10 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) * the throttle. */ p->dl.dl_throttled = 0; - BUG_ON(!is_dl_boosted(&p->dl) || flags != ENQUEUE_REPLENISH); + if (!(flags & ENQUEUE_REPLENISH)) + printk_deferred_once("sched: DL de-boosted task PID %d: REPLENISH flag missing\n", + task_pid_nr(p)); + return; } -- 2.20.1