2017-03-12 09:38:53

by Vegard Nossum

Subject: [PATCH] um: use KERN_CONT in stack dump

Without KERN_CONT, the symbol will appear on a new line, making stack
traces completely unreadable:

Call Trace:
[<6008e891>] ?
printk+0x0/0x94
[<6001cce6>]
show_stack+0xfe/0x15b
[<600666ec>] ?
dump_stack_print_info+0xe1/0xea
[<6008e891>] ?
printk+0x0/0x94
[<6023e826>] ?
bust_spinlocks+0x0/0x4f
[<602343b8>]
dump_stack+0x2a/0x2c
[<6008e662>]
panic+0x170/0x31e
[<6008e4f2>] ?
panic+0x0/0x31e

This makes it readable again:

Call Trace:
[<6008e891>] ? printk+0x0/0x94
[<6001cce6>] show_stack+0xfe/0x15b
[<600666ec>] ? dump_stack_print_info+0xe1/0xea
[<6008e891>] ? printk+0x0/0x94
[<6023e826>] ? bust_spinlocks+0x0/0x4f
[<602343b8>] dump_stack+0x2a/0x2c
[<6008e662>] panic+0x170/0x31e

Signed-off-by: Vegard Nossum <[email protected]>
---
arch/um/kernel/sysrq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
index a76295f7ede9..edf1f80123e7 100644
--- a/arch/um/kernel/sysrq.c
+++ b/arch/um/kernel/sysrq.c
@@ -22,7 +22,7 @@ static void _print_addr(void *data, unsigned long address, int reliable)
{
pr_info(" [<%08lx>]", address);
pr_cont(" %s", reliable ? "" : "? ");
- print_symbol("%s", address);
+ print_symbol(KERN_CONT "%s", address);
pr_cont("\n");
}

--
2.12.0.rc0

2017-03-12 09:45:16

by Richard Weinberger

Subject: Re: [PATCH] um: use KERN_CONT in stack dump

Vegard,

Am 12.03.2017 um 10:38 schrieb Vegard Nossum:
> Without KERN_CONT, the symbol will appear on a new line, making stack
> traces completely unreadable:
>
> Call Trace:
> [<6008e891>] ?
> printk+0x0/0x94
> [<6001cce6>]
> show_stack+0xfe/0x15b
> [<600666ec>] ?
> dump_stack_print_info+0xe1/0xea
> [<6008e891>] ?
> printk+0x0/0x94
> [<6023e826>] ?
> bust_spinlocks+0x0/0x4f
> [<602343b8>]
> dump_stack+0x2a/0x2c
> [<6008e662>]
> panic+0x170/0x31e
> [<6008e4f2>] ?
> panic+0x0/0x31e
>
> This makes it readable again:
>
> Call Trace:
> [<6008e891>] ? printk+0x0/0x94
> [<6001cce6>] show_stack+0xfe/0x15b
> [<600666ec>] ? dump_stack_print_info+0xe1/0xea
> [<6008e891>] ? printk+0x0/0x94
> [<6023e826>] ? bust_spinlocks+0x0/0x4f
> [<602343b8>] dump_stack+0x2a/0x2c
> [<6008e662>] panic+0x170/0x31e
>
> Signed-off-by: Vegard Nossum <[email protected]>
> ---
> arch/um/kernel/sysrq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
> index a76295f7ede9..edf1f80123e7 100644
> --- a/arch/um/kernel/sysrq.c
> +++ b/arch/um/kernel/sysrq.c
> @@ -22,7 +22,7 @@ static void _print_addr(void *data, unsigned long address, int reliable)
> {
> pr_info(" [<%08lx>]", address);
> pr_cont(" %s", reliable ? "" : "? ");
> - print_symbol("%s", address);
> + print_symbol(KERN_CONT "%s", address);
> pr_cont("\n");
> }
>

I think it is better to fix the root of the problem by using a single printk.
i.e.

diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
index aa1b56f5ac68..18eddf677ec6 100644
--- a/arch/um/kernel/sysrq.c
+++ b/arch/um/kernel/sysrq.c
@@ -17,10 +17,8 @@

static void _print_addr(void *data, unsigned long address, int reliable)
{
- pr_info(" [<%08lx>]", address);
- pr_cont(" %s", reliable ? "" : "? ");
- print_symbol("%s", address);
- pr_cont("\n");
+ pr_info(" [<%08lx>] %s%pB\n", address, reliable ? "" : "? ",
+ (void *)address);
}

Thanks,
//richard

2017-03-12 09:48:17

by Vegard Nossum

Subject: Re: [PATCH] um: use KERN_CONT in stack dump

On 12/03/2017 10:45, Richard Weinberger wrote:
> Am 12.03.2017 um 10:38 schrieb Vegard Nossum:
>> Without KERN_CONT, the symbol will appear on a new line, making stack
>> traces completely unreadable:
[snip]
> I think it is better to fix the root of the problem by using a single printk.
> i.e.
>
> diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
> index aa1b56f5ac68..18eddf677ec6 100644
> --- a/arch/um/kernel/sysrq.c
> +++ b/arch/um/kernel/sysrq.c
> @@ -17,10 +17,8 @@
>
> static void _print_addr(void *data, unsigned long address, int reliable)
> {
> - pr_info(" [<%08lx>]", address);
> - pr_cont(" %s", reliable ? "" : "? ");
> - print_symbol("%s", address);
> - pr_cont("\n");
> + pr_info(" [<%08lx>] %s%pB\n", address, reliable ? "" : "? ",
> + (void *)address);
> }

Your patch is better.

Tested-by: Vegard Nossum <[email protected]>

Thanks,


Vegard

2017-04-11 09:36:20

by Vegard Nossum

Subject: Re: [PATCH] um: use KERN_CONT in stack dump

On 12 March 2017 at 10:47, Vegard Nossum <[email protected]> wrote:
> On 12/03/2017 10:45, Richard Weinberger wrote:
>> diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
>> index aa1b56f5ac68..18eddf677ec6 100644
>> --- a/arch/um/kernel/sysrq.c
>> +++ b/arch/um/kernel/sysrq.c
>> @@ -17,10 +17,8 @@
>>
>> static void _print_addr(void *data, unsigned long address, int reliable)
>> {
>> - pr_info(" [<%08lx>]", address);
>> - pr_cont(" %s", reliable ? "" : "? ");
>> - print_symbol("%s", address);
>> - pr_cont("\n");
>> + pr_info(" [<%08lx>] %s%pB\n", address, reliable ? "" : "? ",
>> + (void *)address);
>> }
>
> Tested-by: Vegard Nossum <[email protected]>

Just a heads up, this still appears unfixed in Linus's repo.


Vegard