linux-kernel - Re: [PATCH v3 2/2] mm: mmap: add trace point of vm_unmapped

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Date:   Mon, 30 Mar 2020 13:49:04 +0900
From:   Jaewon Kim <jaewon31.kim@...sung.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     walken@...gle.com, bp@...e.de, akpm@...ux-foundation.org,
        srostedt@...are.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, jaewon31.kim@...il.com
Subject: Re: [PATCH v3 2/2] mm: mmap: add trace point of vm_unmapped_area



On 2020년 03월 30일 01:14, Matthew Wilcox wrote:
> On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
>> +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
>> +		IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
>> +		IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,
> I didn't see the IS_ERR_VALUE problem that Vlastimil mentioned get resolved?
Sorry I missed the problem. And thank you for your comment and suggestion.

I still do not understand why the unlikely incurs [FAILED TO PARSE] problem on trace-cmd.
Then trace log should not use the unlikely?

I may need to resubmit a new patch set with your suggestion.
Thank you
>
> I might suggest ...
>
> +++ b/include/linux/err.h
> @@ -19,7 +19,8 @@
>  
>  #ifndef __ASSEMBLY__
>  
> -#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
> +#define __IS_ERR_VALUE(x) ((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
> +#define IS_ERR_VALUE(x) unlikely(__IS_ERR_VALUE(x))
>  
>  static inline void * __must_check ERR_PTR(long error)
>  {
>
> and then you can use __IS_ERR_VALUE() which removes the unlikely() problem.
>
>