Re: [PATCH v2 4/5] arm64: introduce pfn_valid_region()

From: kbuild test robot <lkp@intel.com>
To: Jia He <hejianet@gmail.com>
Cc: kbuild-all@01.org, Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mel Gorman <mgorman@suse.de>, Will Deacon <will.deacon@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Pavel Tatashin <pasha.tatashin@oracle.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	AKASHI Takahiro <takahiro.akashi@linaro.org>,
	Gioh Kim <gi-oh.kim@profitbricks.com>,
	Steven Sistare <steven.sistare@oracle.com>,
	Daniel Vacek <neelx@redhat.com>,
	Eugeniu Rosca <erosca@de.adit-jv.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	James Morse <james.morse@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Steve Capper <steve.capper@arm.com>,
	x86@kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Kemi Wang <kemi.wang@intel.com>, Petr Tesarik <ptesarik@suse.com>,
	YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Nikolay Borisov <nborisov@suse.com>, Jia He <hejianet@gmail.com>,
	Jia He <jia.he@hxt-semitech.com>
Subject: Re: [PATCH v2 4/5] arm64: introduce pfn_valid_region()
Date: Sun, 25 Mar 2018 22:16:12 +0800	[thread overview]
Message-ID: <201803252220.vUB4M8TF%fengguang.wu@intel.com> (raw)
In-Reply-To: <1521894282-6454-5-git-send-email-hejianet@gmail.com>

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Hi Jia,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on mmotm/master]
[cannot apply to v4.16-rc6]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Jia-He/optimize-memblock_next_valid_pfn-and-early_pfn_valid/20180325-175026
base:   git://git.cmpxchg.org/linux-mmotm.git master
config: arm64-defconfig (attached as .config)
compiler: aarch64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm64 

All warnings (new ones prefixed by >>):

   arch/arm64/mm/init.c: In function 'pfn_valid_region':
>> arch/arm64/mm/init.c:304:35: warning: self-comparison always evaluates to false [-Wtautological-compare]
      if (pfn >= start_pfn && end_pfn < end_pfn)
                                      ^

vim +304 arch/arm64/mm/init.c

   293	
   294	int pfn_valid_region(unsigned long pfn, int *last_idx)
   295	{
   296		unsigned long start_pfn, end_pfn;
   297		struct memblock_type *type = &memblock.memory;
   298	
   299		if (*last_idx != -1) {
   300			start_pfn = PFN_DOWN(type->regions[*last_idx].base);
   301			end_pfn= PFN_DOWN(type->regions[*last_idx].base +
   302						type->regions[*last_idx].size);
   303	
 > 304			if (pfn >= start_pfn && end_pfn < end_pfn)
   305				return !memblock_is_nomap(
   306					&memblock.memory.regions[*last_idx]);
   307		}
   308	
   309		*last_idx = memblock_search_pfn_regions(pfn);
   310		if (*last_idx == -1)
   311			return false;
   312	
   313		return !memblock_is_nomap(&memblock.memory.regions[*last_idx]);
   314	}
   315	EXPORT_SYMBOL(pfn_valid_region);
   316	#endif /*CONFIG_HAVE_ARCH_PFN_VALID*/
   317	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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