This is a note to let you know that I've just added the patch titled
ARC: Call trace_hardirqs_on() before enabling irqs
to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arc-call-trace_hardirqs_on-before-enabling-irqs.patch
and it can be found in the queue-4.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 18b43e89d295cc65151c505c643c98fb2c320e59 Mon Sep 17 00:00:00 2001
From: Daniel Mentz <danielmentz@xxxxxxxxxx>
Date: Thu, 4 Aug 2016 17:56:53 -0700
Subject: ARC: Call trace_hardirqs_on() before enabling irqs
From: Daniel Mentz <danielmentz@xxxxxxxxxx>
commit 18b43e89d295cc65151c505c643c98fb2c320e59 upstream.
trace_hardirqs_on_caller() in lockdep.c expects to be called before, not
after interrupts are actually enabled.
The following comment in kernel/locking/lockdep.c substantiates this
claim:
"
/*
* We're enabling irqs and according to our state above irqs weren't
* already enabled, yet we find the hardware thinks they are in fact
* enabled.. someone messed up their IRQ state tracing.
*/
"
An example can be found in include/linux/irqflags.h:
do { trace_hardirqs_on(); raw_local_irq_enable(); } while (0)
Without this change, we hit the following DEBUG_LOCKS_WARN_ON.
[ 7.760000] ------------[ cut here ]------------
[ 7.760000] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2711 resume_user_mode_begin+0x48/0xf0
[ 7.770000] DEBUG_LOCKS_WARN_ON(!irqs_disabled())
[ 7.780000] Modules linked in:
[ 7.780000] CPU: 0 PID: 1 Comm: init Not tainted 4.7.0-00003-gc668bb9-dirty #366
[ 7.790000]
[ 7.790000] Stack Trace:
[ 7.790000] arc_unwind_core.constprop.1+0xa4/0x118
[ 7.800000] warn_slowpath_fmt+0x72/0x158
[ 7.800000] resume_user_mode_begin+0x48/0xf0
[ 7.810000] ---[ end trace 6f6a7a8fae20d2f0 ]---
Signed-off-by: Daniel Mentz <danielmentz@xxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/include/asm/irqflags-compact.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arc/include/asm/irqflags-compact.h
+++ b/arch/arc/include/asm/irqflags-compact.h
@@ -188,10 +188,10 @@ static inline int arch_irqs_disabled(voi
.endm
.macro IRQ_ENABLE scratch
+ TRACE_ASM_IRQ_ENABLE
lr \scratch, [status32]
or \scratch, \scratch, (STATUS_E1_MASK | STATUS_E2_MASK)
flag \scratch
- TRACE_ASM_IRQ_ENABLE
.endm
#endif /* __ASSEMBLY__ */
Patches currently in stable-queue which might be from danielmentz@xxxxxxxxxx are
queue-4.7/arc-call-trace_hardirqs_on-before-enabling-irqs.patch
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