linux-kernel - Re: [PATCH v4] mm: Add CONFIG_PAGE_BLOCK

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Message-ID: <9A5BA016-179F-4BFF-AB1E-61F39CA0C1C2@nvidia.com>
Date: Tue, 13 May 2025 12:52:16 -0400
From: Zi Yan <ziy@...dia.com>
To: Juan Yescas <jyescas@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 kernel test robot <lkp@...el.com>, <linux-kernel@...r.kernel.org>,
 <oe-kbuild-all@...ts.linux.dev>,
 Linux Memory Management List <linux-mm@...ck.org>, <tjmercier@...gle.com>,
 <isaacmanjarres@...gle.com>, <surenb@...gle.com>, <kaleshsingh@...gle.com>,
 Vlastimil Babka <vbabka@...e.cz>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 David Hildenbrand <david@...hat.com>, Mike Rapoport <rppt@...nel.org>,
 Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH v4] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block
 order

On 13 May 2025, at 12:47, Zi Yan wrote:

> On 13 May 2025, at 12:41, Juan Yescas wrote:
>
>> On Tue, May 13, 2025 at 8:08 AM Zi Yan <ziy@...dia.com> wrote:
>>>
>>> On 10 May 2025, at 13:16, kernel test robot wrote:
>>>
>>>> Hi Juan,
>>>>
>>>> kernel test robot noticed the following build errors:
>>>>
>>>> [auto build test ERROR on linus/master]
>>>> [also build test ERROR on v6.15-rc5]
>>>> [cannot apply to akpm-mm/mm-everything next-20250509]
>>>> [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/Juan-Yescas/mm-Add-CONFIG_PAGE_BLOCK_ORDER-to-select-page-block-order/20250510-090501
>>>> base:   linus/master
>>>> patch link:    https://lore.kernel.org/r/20250510010338.3978696-1-jyescas%40google.com
>>>> patch subject: [PATCH v4] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block order
>>>> config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20250511/202505110035.wtOWnL8o-lkp@intel.com/config)
>>>> compiler: powerpc64-linux-gcc (GCC) 14.2.0
>>>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250511/202505110035.wtOWnL8o-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/202505110035.wtOWnL8o-lkp@intel.com/
>>>>
>>>> All errors (new ones prefixed by >>):
>>>>
>>>>    In file included from include/linux/gfp.h:7,
>>>>                     from include/linux/xarray.h:16,
>>>>                     from include/linux/list_lru.h:14,
>>>>                     from include/linux/fs.h:14,
>>>>                     from include/linux/compat.h:17,
>>>>                     from arch/powerpc/kernel/asm-offsets.c:12:
>>>>>> include/linux/mmzone.h:53:2: error: #error MAX_PAGE_ORDER must be >= PAGE_BLOCK_ORDER
>>>>       53 | #error MAX_PAGE_ORDER must be >= PAGE_BLOCK_ORDER
>>>>          |  ^~~~~
>>>>    make[3]: *** [scripts/Makefile.build:98: arch/powerpc/kernel/asm-offsets.s] Error 1
>>>
>>> In this config, CONFIG_ARCH_FORCE_MAX_ORDER is set to 8, lower than
>>> the default PAGE_BLOCK_ORDER value, 10. I wonder if the error should
>>> be changed to ignore CONFIG_PAGE_BLOCK_ORDER when MAX_PAGE_ORDER is
>>> set by CONFIG_ARCH_FORCE_MAX_ORDER and give a warning instead.
>>
>> In ARMv8, MAX_PAGE_ORDER is set up by CONFIG_ARCH_FORCE_MAX_ORDER
>> and CONFIG_PAGE_BLOCK_ORDER is also set up, so we need to take into account
>> CONFIG_PAGE_BLOCK_ORDER. For other architectures, the default will be:
>> CONFIG_ARCH_FORCE_MAX_ORDER = CONFIG_PAGE_BLOCK_ORDER.
>
> It seems that the Kconfig “range 1 ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER”
> is not working. The above powerpc-allmodconfig has CONFIG_ARCH_FORCE_MAX_ORDER
> set to 8 and CONFIG_PAGE_BLOCK_ORDER is set to 10, leading to the compilation
> error.

You can get the same config by running “ARCH=powerpc make allmodconfig”.

>
>>
>> Is there any valid case where the MAX_PAGE_ORDER needs to be smaller than
>> the page block order?
>
> I am not aware of any.
>
>>
>> Thanks
>> Juan
>>>
>>>>    make[3]: Target 'prepare' not remade because of errors.
>>>>    make[2]: *** [Makefile:1275: prepare0] Error 2
>>>>    make[2]: Target 'prepare' not remade because of errors.
>>>>    make[1]: *** [Makefile:248: __sub-make] Error 2
>>>>    make[1]: Target 'prepare' not remade because of errors.
>>>>    make: *** [Makefile:248: __sub-make] Error 2
>>>>    make: Target 'prepare' not remade because of errors.
>>>>
>>>>
>>>> vim +53 include/linux/mmzone.h
>>>>
>>>>     46
>>>>     47        /*
>>>>     48         * The MAX_PAGE_ORDER, which defines the max order of pages to be allocated
>>>>     49         * by the buddy allocator, has to be larger or equal to the PAGE_BLOCK_ORDER,
>>>>     50         * which defines the order for the number of pages that can have a migrate type
>>>>     51         */
>>>>     52        #if (PAGE_BLOCK_ORDER > MAX_PAGE_ORDER)
>>>>   > 53        #error MAX_PAGE_ORDER must be >= PAGE_BLOCK_ORDER
>>>>     54        #endif
>>>>     55
>>>>
>>>> --
>>>> 0-DAY CI Kernel Test Service
>>>> https://github.com/intel/lkp-tests/wiki
>>>
>>>
>>> Best Regards,
>>> Yan, Zi
>
>
> Best Regards,
> Yan, Zi


Best Regards,
Yan, Zi