diff options
| author | Wanpeng Li <wanpeng.li@hotmail.com> | 2016-09-18 19:34:51 +0800 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2017-01-27 17:15:00 +0100 |
| commit | a2b17a74c58b0a6ac4c7bd1c1c64f00eaadadfce (patch) | |
| tree | 2465852d39f21ea6987e697e6dce6d0d25eed1a1 | |
| parent | 75e8aab4ba77c566a538bd85b0324ae71cc5a5ed (diff) | |
x86/apic: Order irq_enter/exit() calls correctly vs. ack_APIC_irq()
commit b0f48706a176b71a6e54f399d7404bbeeaa7cfab upstream.
===============================
[ INFO: suspicious RCU usage. ]
4.8.0-rc6+ #5 Not tainted
-------------------------------
./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
no locks held by swapper/2/0.
stack backtrace:
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.8.0-rc6+ #5
Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015
0000000000000000 ffff8d1bd6003f10 ffffffff94446949 ffff8d1bd4a68000
0000000000000001 ffff8d1bd6003f40 ffffffff940e9247 ffff8d1bbdfcf3d0
000000000000080b 0000000000000000 0000000000000000 ffff8d1bd6003f70
Call Trace:
<IRQ> [<ffffffff94446949>] dump_stack+0x99/0xd0
[<ffffffff940e9247>] lockdep_rcu_suspicious+0xe7/0x120
[<ffffffff9448e0d5>] do_trace_write_msr+0x135/0x140
[<ffffffff9406e750>] native_write_msr+0x20/0x30
[<ffffffff9406503d>] native_apic_msr_eoi_write+0x1d/0x30
[<ffffffff9405b17e>] smp_trace_call_function_interrupt+0x1e/0x270
[<ffffffff948cb1d6>] trace_call_function_interrupt+0x96/0xa0
<EOI> [<ffffffff947200f4>] ? cpuidle_enter_state+0xe4/0x360
[<ffffffff947200df>] ? cpuidle_enter_state+0xcf/0x360
[<ffffffff947203a7>] cpuidle_enter+0x17/0x20
[<ffffffff940df008>] cpu_startup_entry+0x338/0x4d0
[<ffffffff9405bfc4>] start_secondary+0x154/0x180
This can be reproduced readily by running ftrace test case of kselftest.
Move the irq_enter() call before ack_APIC_irq(), because irq_enter() tells
the RCU susbstems to end the extended quiescent state, so that the
following trace call in ack_APIC_irq() works correctly. The same applies to
exiting_ack_irq() which calls ack_APIC_irq() after irq_exit().
[ tglx: Massaged changelog ]
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474198491-3738-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | arch/x86/include/asm/apic.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/smp.c | 2 |
2 files changed, 2 insertions, 3 deletions
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 29559831c94f..43849c3d6275 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -710,9 +710,8 @@ static inline void exiting_irq(void) static inline void exiting_ack_irq(void) { - irq_exit(); - /* Ack only at the end to avoid potential reentry */ ack_APIC_irq(); + irq_exit(); } extern void ioapic_zap_locks(void); diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 7c3a5a61f2e4..e5d895fa1fe0 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -267,8 +267,8 @@ __visible void smp_reschedule_interrupt(struct pt_regs *regs) static inline void smp_entering_irq(void) { - ack_APIC_irq(); irq_enter(); + ack_APIC_irq(); } __visible void smp_trace_reschedule_interrupt(struct pt_regs *regs) |