Re: [PATCH v2 4/7] mm: page_owner: add support for splitting to any order in split page_owner.

[Zi Yan <ziy@nvidia.com>]

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On 29 Mar 2023, at 5:58, kernel test robot wrote:

> Hi Zi,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on akpm-mm/mm-everything]
> [also build test ERROR on linus/master v6.3-rc4 next-20230329]
> [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/Zi-Yan/mm-memcg-use-order-instead-of-nr-in-split_page_memcg/20230329-091809
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link:    https://lore.kernel.org/r/20230329011712.3242298-5-zi.yan%40sent.com
> patch subject: [PATCH v2 4/7] mm: page_owner: add support for splitting to any order in split page_owner.
> config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20230329/202303291732.7OqWI96E-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> reproduce (this is a W=1 build):
>         # https://github.com/intel-lab-lkp/linux/commit/6d1831c0e01a1a742e026454fe6e5643e08c5985
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Zi-Yan/mm-memcg-use-order-instead-of-nr-in-split_page_memcg/20230329-091809
>         git checkout 6d1831c0e01a1a742e026454fe6e5643e08c5985
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         make W=1 O=build_dir ARCH=i386 olddefconfig
>         make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Link: https://lore.kernel.org/oe-kbuild-all/202303291732.7OqWI96E-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
>    mm/page_owner.c: In function '__split_page_owner':
>>> mm/page_owner.c:226:28: error: implicit declaration of function 'lookup_page_ext' [-Werror=implicit-function-declaration]
>      226 |                 page_ext = lookup_page_ext(page + i);
>          |                            ^~~~~~~~~~~~~~~
>    mm/page_owner.c:226:26: warning: assignment to 'struct page_ext *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
>      226 |                 page_ext = lookup_page_ext(page + i);
>          |                          ^
>    cc1: some warnings being treated as errors
>
>
> vim +/lookup_page_ext +226 mm/page_owner.c
>
>    213	
>    214	void __split_page_owner(struct page *page, int old_order, int new_order)
>    215	{
>    216		int i;
>    217		struct page_ext *page_ext = page_ext_get(page);
>    218		struct page_owner *page_owner;
>    219		unsigned int old_nr = 1 << old_order;
>    220		unsigned int new_nr = 1 << new_order;
>    221	
>    222		if (unlikely(!page_ext))
>    223			return;
>    224	
>    225		for (i = 0; i < old_nr; i += new_nr) {
>> 226			page_ext = lookup_page_ext(page + i);
>    227			page_owner = get_page_owner(page_ext);
>    228			page_owner->order = new_order;
>    229		}
>    230		page_ext_put(page_ext);
>    231	}
>    232	
>
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests

It can be fixed by the patch below. I will fix it in the next version. Thanks.

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 347861fe9c50..72244a4f1a31 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -223,9 +223,9 @@ void __split_page_owner(struct page *page, int old_order, int new_order)
                return;

        for (i = 0; i < old_nr; i += new_nr) {
-               page_ext = lookup_page_ext(page + i);
                page_owner = get_page_owner(page_ext);
                page_owner->order = new_order;
+               page_ext = page_ext_next(page_ext);
        }
        page_ext_put(page_ext);
 }


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Best Regards,
Yan, Zi

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