linux-kernel - [PATCH 5.4 115/178] sched/deadline: Initialize ->dl

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Date:   Mon, 29 Jun 2020 11:24:20 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Juri Lelli <juri.lelli@...hat.com>,
        syzbot+5ac8bac25f95e8b221e7@...kaller.appspotmail.com,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Daniel Wagner <dwagner@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 115/178] sched/deadline: Initialize ->dl_boosted

From: Juri Lelli <juri.lelli@...hat.com>

[ Upstream commit ce9bc3b27f2a21a7969b41ffb04df8cf61bd1592 ]

syzbot reported the following warning triggered via SYSC_sched_setattr():

  WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 setup_new_dl_entity /kernel/sched/deadline.c:594 [inline]
  WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 enqueue_dl_entity /kernel/sched/deadline.c:1370 [inline]
  WARNING: CPU: 0 PID: 6973 at kernel/sched/deadline.c:593 enqueue_task_dl+0x1c17/0x2ba0 /kernel/sched/deadline.c:1441

This happens because the ->dl_boosted flag is currently not initialized by
__dl_clear_params() (unlike the other flags) and setup_new_dl_entity()
rightfully complains about it.

Initialize dl_boosted to 0.

Fixes: 2d3d891d3344 ("sched/deadline: Add SCHED_DEADLINE inheritance logic")
Reported-by: syzbot+5ac8bac25f95e8b221e7@...kaller.appspotmail.com
Signed-off-by: Juri Lelli <juri.lelli@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Tested-by: Daniel Wagner <dwagner@...e.de>
Link: https://lkml.kernel.org/r/20200617072919.818409-1-juri.lelli@redhat.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/sched/deadline.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 08bdee0480b3e..4cb00538a207b 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2693,6 +2693,7 @@ void __dl_clear_params(struct task_struct *p)
 	dl_se->dl_bw			= 0;
 	dl_se->dl_density		= 0;
 
+	dl_se->dl_boosted		= 0;
 	dl_se->dl_throttled		= 0;
 	dl_se->dl_yielded		= 0;
 	dl_se->dl_non_contending	= 0;
-- 
2.25.1