[2/2] MIPS: Fix kernel hang under FUNCTION_GRAPH_TRACER and PREEMPT_TRACER
diff mbox series

Message ID 1621076521-22412-3-git-send-email-yangtiezhu@loongson.cn
State New, archived
Headers show
Series
  • Update defconfig and fix kernel hang
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Commit Message

Tiezhu Yang May 15, 2021, 11:02 a.m. UTC
When update the latest mainline kernel with the following three configs,
the kernel hangs during startup:

(1) CONFIG_FUNCTION_GRAPH_TRACER=y
(2) CONFIG_PREEMPT_TRACER=y
(3) CONFIG_FTRACE_STARTUP_TEST=y

When update the latest mainline kernel with the above two configs (1)
and (2), the kernel starts normally, but it still hangs when execute
the following command:

echo "function_graph" > /sys/kernel/debug/tracing/current_tracer

Without CONFIG_PREEMPT_TRACER=y, the above two kinds of kernel hangs
disappeared, so it seems that CONFIG_PREEMPT_TRACER has some influences
with function_graph tracer at the first glance.

I use ejtag to find out the epc address is related with preempt_enable()
in the file arch/mips/lib/mips-atomic.c, because function tracing can
trace the preempt_{enable,disable} calls that are traced, replace them
with preempt_{enable,disable}_notrace to prevent function tracing from
going into an infinite loop, and then it can fix the kernel hang issue.

By the way, it seems that this commit is a complement and improvement of
commit f93a1a00f2bd ("MIPS: Fix crash that occurs when function tracing
is enabled").

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 arch/mips/lib/mips-atomic.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Comments

Thomas Bogendoerfer May 25, 2021, 1:38 p.m. UTC | #1
On Sat, May 15, 2021 at 07:02:01PM +0800, Tiezhu Yang wrote:
> When update the latest mainline kernel with the following three configs,
> the kernel hangs during startup:
> 
> (1) CONFIG_FUNCTION_GRAPH_TRACER=y
> (2) CONFIG_PREEMPT_TRACER=y
> (3) CONFIG_FTRACE_STARTUP_TEST=y
> 
> When update the latest mainline kernel with the above two configs (1)
> and (2), the kernel starts normally, but it still hangs when execute
> the following command:
> 
> echo "function_graph" > /sys/kernel/debug/tracing/current_tracer
> 
> Without CONFIG_PREEMPT_TRACER=y, the above two kinds of kernel hangs
> disappeared, so it seems that CONFIG_PREEMPT_TRACER has some influences
> with function_graph tracer at the first glance.
> 
> I use ejtag to find out the epc address is related with preempt_enable()
> in the file arch/mips/lib/mips-atomic.c, because function tracing can
> trace the preempt_{enable,disable} calls that are traced, replace them
> with preempt_{enable,disable}_notrace to prevent function tracing from
> going into an infinite loop, and then it can fix the kernel hang issue.
> 
> By the way, it seems that this commit is a complement and improvement of
> commit f93a1a00f2bd ("MIPS: Fix crash that occurs when function tracing
> is enabled").
> 
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> ---
>  arch/mips/lib/mips-atomic.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)

applied to mips-fixes.

Thomas.

Patch
diff mbox series

diff --git a/arch/mips/lib/mips-atomic.c b/arch/mips/lib/mips-atomic.c
index de03838..a9b72ea 100644
--- a/arch/mips/lib/mips-atomic.c
+++ b/arch/mips/lib/mips-atomic.c
@@ -37,7 +37,7 @@ 
  */
 notrace void arch_local_irq_disable(void)
 {
-	preempt_disable();
+	preempt_disable_notrace();
 
 	__asm__ __volatile__(
 	"	.set	push						\n"
@@ -53,7 +53,7 @@  notrace void arch_local_irq_disable(void)
 	: /* no inputs */
 	: "memory");
 
-	preempt_enable();
+	preempt_enable_notrace();
 }
 EXPORT_SYMBOL(arch_local_irq_disable);
 
@@ -61,7 +61,7 @@  notrace unsigned long arch_local_irq_save(void)
 {
 	unsigned long flags;
 
-	preempt_disable();
+	preempt_disable_notrace();
 
 	__asm__ __volatile__(
 	"	.set	push						\n"
@@ -78,7 +78,7 @@  notrace unsigned long arch_local_irq_save(void)
 	: /* no inputs */
 	: "memory");
 
-	preempt_enable();
+	preempt_enable_notrace();
 
 	return flags;
 }
@@ -88,7 +88,7 @@  notrace void arch_local_irq_restore(unsigned long flags)
 {
 	unsigned long __tmp1;
 
-	preempt_disable();
+	preempt_disable_notrace();
 
 	__asm__ __volatile__(
 	"	.set	push						\n"
@@ -106,7 +106,7 @@  notrace void arch_local_irq_restore(unsigned long flags)
 	: "0" (flags)
 	: "memory");
 
-	preempt_enable();
+	preempt_enable_notrace();
 }
 EXPORT_SYMBOL(arch_local_irq_restore);