linux-kernel - [PATCH] sched/deadline: Initialize dl

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Date:   Wed, 17 Jun 2020 09:29:19 +0200
From:   Juri Lelli <juri.lelli@...hat.com>
To:     peterz@...radead.org, mingo@...hat.com
Cc:     vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, dwagner@...e.de, linux-kernel@...r.kernel.org,
        luca.abeni@...tannapisa.it, bristot@...hat.com,
        Juri Lelli <juri.lelli@...hat.com>,
        syzbot+5ac8bac25f95e8b221e7@...kaller.appspotmail.com
Subject: [PATCH] sched/deadline: Initialize dl_boosted

syzbot reported the following warning:

  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
  Kernel panic - not syncing: panic_on_warn set ...

  CPU: 0 PID: 6973 Comm: syz-executor366 Not tainted 4.14.133 #28
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  Call Trace:
   __dump_stack /lib/dump_stack.c:17 [inline]
   dump_stack+0x138/0x19c /lib/dump_stack.c:53
   panic+0x1f2/0x426 /kernel/panic.c:182
   __warn.cold+0x2f/0x36 /kernel/panic.c:546
   report_bug+0x216/0x254 /lib/bug.c:186
   fixup_bug /arch/x86/kernel/traps.c:177 [inline]
   fixup_bug /arch/x86/kernel/traps.c:172 [inline]
   do_error_trap+0x1bb/0x310 /arch/x86/kernel/traps.c:295
   do_invalid_op+0x1b/0x20 /arch/x86/kernel/traps.c:314
   invalid_op+0x1b/0x40 /arch/x86/entry/entry_64.S:960
  RIP: 0010:setup_new_dl_entity /kernel/sched/deadline.c:593 [inline]
  RIP: 0010:enqueue_dl_entity /kernel/sched/deadline.c:1370 [inline]
  RIP: 0010:enqueue_task_dl+0x1c17/0x2ba0 /kernel/sched/deadline.c:1441
  RSP: 0018:ffff888098a3fcd8 EFLAGS: 00010002
  RAX: 0000000000000000 RBX: ffffffff87ab2780 RCX: 1ffff1101041413a
  RDX: 0000000ad48fb497 RSI: ffff8880aee2c518 RDI: ffff8880820a09d0
  RBP: ffff888098a3fd48 R08: ffff8880820a09cc R09: ffff8880820a09c0
  R10: ffff8880820a073c R11: 0000000000000001 R12: ffff8880820a0700
  R13: ffff8880aee2c500 R14: ffff8880820a0978 R15: ffff8880aee2c500
   enqueue_task /kernel/sched/core.c:762 [inline]
   __sched_setscheduler+0xd17/0x2510 /kernel/sched/core.c:4227
   sched_setattr /kernel/sched/core.c:4285 [inline]
   SYSC_sched_setattr /kernel/sched/core.c:4456 [inline]
   SyS_sched_setattr+0x1f8/0x300 /kernel/sched/core.c:4435
   do_syscall_64+0x1e8/0x640 /arch/x86/entry/common.c:292
   entry_SYSCALL_64_after_hwframe+0x42/0xb7
  RIP: 0033:0x446749
  RSP: 002b:00007ff022092db8 EFLAGS: 00000246 ORIG_RAX: 000000000000013a
  RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446749
  RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000
  RBP: 00000000006dbc30 R08: 00007ff022093700 R09: 0000000000000000
  R10: 00007ff022093700 R11: 0000000000000246 R12: 00000000006dbc3c
  R13: 00007ffdbf86bf7f R14: 00007ff0220939c0 R15: 0000000000000000

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

Initialize dl_boosted to 0.

Reported-by: syzbot+5ac8bac25f95e8b221e7@...kaller.appspotmail.com
Signed-off-by: Juri Lelli <juri.lelli@...hat.com>
Tested-by: Daniel Wagner <dwagner@...e.de>
---
 kernel/sched/deadline.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 504d2f51b0d6..f63f337c7147 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2692,6 +2692,7 @@ 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;
-- 
2.26.2