linux-kernel - Re: [PATCH v1 05/12] mm: thp: introduce folio_split_queue_lock{

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Date:   Sat, 14 Aug 2021 18:38:33 +0800
From:   kernel test robot <lkp@...el.com>
To:     Muchun Song <songmuchun@...edance.com>, guro@...com,
        hannes@...xchg.org, mhocko@...nel.org, akpm@...ux-foundation.org,
        shakeelb@...gle.com, vdavydov.dev@...il.com
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, duanxiongchun@...edance.com,
        fam.zheng@...edance.com
Subject: Re: [PATCH v1 05/12] mm: thp: introduce
 folio_split_queue_lock{_irqsave}()

Hi Muchun,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on next-20210813]
[cannot apply to hnaz-linux-mm/master cgroup/for-next linus/master v5.14-rc5 v5.14-rc4 v5.14-rc3 v5.14-rc5]
[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]

url:    https://github.com/0day-ci/linux/commits/Muchun-Song/Use-obj_cgroup-APIs-to-charge-the-LRU-pages/20210814-132844
base:    4b358aabb93a2c654cd1dcab1a25a589f6e2b153
config: sparc64-randconfig-p002-20210814 (attached as .config)
compiler: sparc64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/3460bcf13b968edf6f4621c0e0dcde46500957e5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Muchun-Song/Use-obj_cgroup-APIs-to-charge-the-LRU-pages/20210814-132844
        git checkout 3460bcf13b968edf6f4621c0e0dcde46500957e5
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=sparc64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   mm/huge_memory.c: In function 'deferred_split_huge_page':
>> mm/huge_memory.c:2797:28: warning: variable 'memcg' set but not used [-Wunused-but-set-variable]
    2797 |         struct mem_cgroup *memcg;
         |                            ^~~~~


vim +/memcg +2797 mm/huge_memory.c

  2793	
  2794	void deferred_split_huge_page(struct page *page)
  2795	{
  2796		struct deferred_split *ds_queue;
> 2797		struct mem_cgroup *memcg;
  2798		unsigned long flags;
  2799	
  2800		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
  2801	
  2802		/*
  2803		 * The try_to_unmap() in page reclaim path might reach here too,
  2804		 * this may cause a race condition to corrupt deferred split queue.
  2805		 * And, if page reclaim is already handling the same page, it is
  2806		 * unnecessary to handle it again in shrinker.
  2807		 *
  2808		 * Check PageSwapCache to determine if the page is being
  2809		 * handled by page reclaim since THP swap would add the page into
  2810		 * swap cache before calling try_to_unmap().
  2811		 */
  2812		if (PageSwapCache(page))
  2813			return;
  2814	
  2815		ds_queue = folio_split_queue_lock_irqsave(page_folio(page), &flags);
  2816		memcg = split_queue_memcg(ds_queue);
  2817		if (list_empty(page_deferred_list(page))) {
  2818			count_vm_event(THP_DEFERRED_SPLIT_PAGE);
  2819			list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
  2820			ds_queue->split_queue_len++;
  2821	#ifdef CONFIG_MEMCG
  2822			if (memcg)
  2823				set_shrinker_bit(memcg, page_to_nid(page),
  2824						 deferred_split_shrinker.id);
  2825	#endif
  2826		}
  2827		split_queue_unlock_irqrestore(ds_queue, flags);
  2828	}
  2829	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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