lkml.org 
[lkml]   [2020]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH AUTOSEL 5.4 24/24] arm64/smp: Move rcu_cpu_starting() earlier
Date
From: Qian Cai <cai@redhat.com>

[ Upstream commit ce3d31ad3cac765484463b4f5a0b6b1f8f1a963e ]

The call to rcu_cpu_starting() in secondary_start_kernel() is not early
enough in the CPU-hotplug onlining process, which results in lockdep
splats as follows:

WARNING: suspicious RCU usage
-----------------------------
kernel/locking/lockdep.c:3497 RCU-list traversed in non-reader section!!

other info that might help us debug this:

RCU used illegally from offline CPU!
rcu_scheduler_active = 1, debug_locks = 1
no locks held by swapper/1/0.

Call trace:
dump_backtrace+0x0/0x3c8
show_stack+0x14/0x60
dump_stack+0x14c/0x1c4
lockdep_rcu_suspicious+0x134/0x14c
__lock_acquire+0x1c30/0x2600
lock_acquire+0x274/0xc48
_raw_spin_lock+0xc8/0x140
vprintk_emit+0x90/0x3d0
vprintk_default+0x34/0x40
vprintk_func+0x378/0x590
printk+0xa8/0xd4
__cpuinfo_store_cpu+0x71c/0x868
cpuinfo_store_cpu+0x2c/0xc8
secondary_start_kernel+0x244/0x318

This is avoided by moving the call to rcu_cpu_starting up near the
beginning of the secondary_start_kernel() function.

Signed-off-by: Qian Cai <cai@redhat.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/
Link: https://lore.kernel.org/r/20201028182614.13655-1-cai@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kernel/smp.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 102dc3e7f2e1d..426409e0d0713 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -215,6 +215,7 @@ asmlinkage notrace void secondary_start_kernel(void)
if (system_uses_irq_prio_masking())
init_gic_priority_masking();

+ rcu_cpu_starting(cpu);
preempt_disable();
trace_hardirqs_off();

--
2.27.0
\
 
 \ /
  Last update: 2020-11-03 02:24    [W:0.239 / U:0.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site