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Message-Id: <20230120150246.20797-3-wander@redhat.com>
Date: Fri, 20 Jan 2023 12:02:40 -0300
From: Wander Lairson Costa <wander@...hat.com>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Valentin Schneider <vschneid@...hat.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Catalin Marinas <catalin.marinas@....com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Wander Lairson Costa <wander@...hat.com>,
Oleg Nesterov <oleg@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Andy Lutomirski <luto@...nel.org>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Fenghua Yu <fenghua.yu@...el.com>,
Andrei Vagin <avagin@...il.com>,
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 2/4] sched/deadline: fix inactive_task_timer splat
inactive_task_timer() executes in interrupt (atomic) context. It calls
put_task_struct(), which indirectly acquires sleeping locks under
PREEMPT_RT.
Below is an example of a splat that happened in a test environment:
CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W ---------
Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012
Call Trace:
dump_stack_lvl+0x57/0x7d
mark_lock_irq.cold+0x33/0xba
? stack_trace_save+0x4b/0x70
? save_trace+0x55/0x150
mark_lock+0x1e7/0x400
mark_usage+0x11d/0x140
__lock_acquire+0x30d/0x930
lock_acquire.part.0+0x9c/0x210
? refill_obj_stock+0x3d/0x3a0
? rcu_read_lock_sched_held+0x3f/0x70
? trace_lock_acquire+0x38/0x140
? lock_acquire+0x30/0x80
? refill_obj_stock+0x3d/0x3a0
rt_spin_lock+0x27/0xe0
? refill_obj_stock+0x3d/0x3a0
refill_obj_stock+0x3d/0x3a0
? inactive_task_timer+0x1ad/0x340
kmem_cache_free+0x357/0x560
inactive_task_timer+0x1ad/0x340
? switched_from_dl+0x2d0/0x2d0
__run_hrtimer+0x8a/0x1a0
__hrtimer_run_queues+0x91/0x130
hrtimer_interrupt+0x10f/0x220
__sysvec_apic_timer_interrupt+0x7b/0xd0
sysvec_apic_timer_interrupt+0x4f/0xd0
? asm_sysvec_apic_timer_interrupt+0xa/0x20
asm_sysvec_apic_timer_interrupt+0x12/0x20
RIP: 0033:0x7fff196bf6f5
Use put_task_struct_atomic_safe() instead.
Signed-off-by: Wander Lairson Costa <wander@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
kernel/sched/deadline.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 0d97d54276cc..03400c61a994 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1442,7 +1442,7 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
dl_se->dl_non_contending = 0;
unlock:
task_rq_unlock(rq, p, &rf);
- put_task_struct(p);
+ put_task_struct_atomic_safe(p);
return HRTIMER_NORESTART;
}
--
2.39.0
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