linux-kernel - Re: [PATCH v3 6/9] x86: kdump: use generic interface to simplify crashkernel reservation code

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Message-ID: <ZQRYixr2AtJtRFrh@MiWiFi-R3L-srv>
Date:   Fri, 15 Sep 2023 21:13:47 +0800
From:   Baoquan He <bhe@...hat.com>
To:     kernel test robot <lkp@...el.com>, akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        oe-kbuild-all@...ts.linux.dev, akpm@...ux-foundation.org,
        thunder.leizhen@...wei.com, catalin.marinas@....com,
        chenjiahao16@...wei.com, kexec@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, x86@...nel.org
Subject: Re: [PATCH v3 6/9] x86: kdump: use generic interface to simplify
 crashkernel reservation code

On 09/14/23 at 04:12pm, kernel test robot wrote:
> Hi Baoquan,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on powerpc/next]
> [also build test WARNING on powerpc/fixes linus/master v6.6-rc1 next-20230914]
> [cannot apply to arm64/for-next/core tip/x86/core]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Baoquan-He/crash_core-c-remove-unnecessary-parameter-of-function/20230914-113546
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
> patch link:    https://lore.kernel.org/r/20230914033142.676708-7-bhe%40redhat.com
> patch subject: [PATCH v3 6/9] x86: kdump: use generic interface to simplify crashkernel reservation code
> config: i386-allnoconfig (https://download.01.org/0day-ci/archive/20230914/202309141534.moH4dTcz-lkp@intel.com/config)
> compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230914/202309141534.moH4dTcz-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202309141534.moH4dTcz-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> arch/x86/kernel/setup.c:476:15: warning: no previous prototype for function 'crash_low_size_default' [-Wmissing-prototypes]
>    unsigned long crash_low_size_default(void)
>                  ^
>    arch/x86/kernel/setup.c:476:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    unsigned long crash_low_size_default(void)
>    ^
>    static 
>    1 warning generated.

Thanks for reporting this. I can reproduced this warning on x86_64
machine by retrieving the LKP's config and build it with below command:

	make ARCH=i386 -j128 W=1 arch/x86/kernel/

I can fix it by moving crash_low_size_default() into arch/x86/include/asm/crash_core.h 
and make it as static inline as below draft change.

Hi Andrew,

I should post v4 of the whole series or just v4 of this patch?

[PATCH v3 6/9] x86: kdump: use generic interface to simplify crashkernel reservation code


diff --git a/arch/x86/include/asm/crash_core.h b/arch/x86/include/asm/crash_core.h
index 5fc5e4f94521..76af98f4e801 100644
--- a/arch/x86/include/asm/crash_core.h
+++ b/arch/x86/include/asm/crash_core.h
@@ -18,6 +18,7 @@
  * no good way to detect the paging mode of the target kernel which will be
  * loaded for dumping.
  */
+extern unsigned long swiotlb_size_or_default(void);
 
 #ifdef CONFIG_X86_32
 # define CRASH_ADDR_LOW_MAX     SZ_512M
@@ -29,6 +30,13 @@
 
 # define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
 
-extern unsigned long crash_low_size_default(void);
+static inline unsigned long crash_low_size_default(void)
+{
+#ifdef CONFIG_X86_64
+	return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
+#else
+	return 0;
+#endif
+}
 
 #endif /* _X86_CRASH_CORE_H */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 0acc86587fc0..d7baa567c68e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -470,18 +470,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 	}
 }
 
-/*
- * --------- Crashkernel reservation ------------------------------
- */
-unsigned long crash_low_size_default(void)
-{
-#ifdef CONFIG_X86_64
-	return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
-#else
-	return 0;
-#endif
-}
-
 static void __init arch_reserve_crashkernel(void)
 {
 	unsigned long long crash_base, crash_size, low_size = 0;