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

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Date:   Sun, 29 Mar 2020 09:14:10 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Jaewon Kim <jaewon31.kim@...sung.com>
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 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?

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.