Re: [PATCH v9 74/96] mm/workingset: Convert workingset_refault to take a folio

[kernel test robot <lkp@intel.com>]

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Hi "Matthew,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20210505]
[cannot apply to hnaz-linux-mm/master xfs-linux/for-next tip/perf/core shaggy/jfs-next block/for-next linus/master asm-generic/master v5.12 v5.12-rc8 v5.12-rc7 v5.12]
[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/Matthew-Wilcox-Oracle/Memory-folios/20210506-014108
base:    29955e0289b3255c5f609a7564a0f0bb4ae35c7a
config: nds32-defconfig (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0
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/b1883a3797e1623bf783141c25482fee16e1031c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/Memory-folios/20210506-014108
        git checkout b1883a3797e1623bf783141c25482fee16e1031c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=nds32 

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

All error/warnings (new ones prefixed by >>):

   In file included from mm/workingset.c:8:
   include/linux/memcontrol.h: In function 'folio_uncharge_cgroup':
   include/linux/memcontrol.h:1213:42: error: parameter name omitted
    1213 | static inline void folio_uncharge_cgroup(struct folio *)
         |                                          ^~~~~~~~~~~~~~
   mm/workingset.c: In function 'unpack_shadow':
   mm/workingset.c:201:15: warning: variable 'nid' set but not used [-Wunused-but-set-variable]
     201 |  int memcgid, nid;
         |               ^~~
   mm/workingset.c: In function 'workingset_refault':
>> mm/workingset.c:348:10: error: implicit declaration of function 'folio_memcg' [-Werror=implicit-function-declaration]
     348 |  memcg = folio_memcg(folio);
         |          ^~~~~~~~~~~
>> mm/workingset.c:348:8: warning: assignment to 'struct mem_cgroup *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
     348 |  memcg = folio_memcg(folio);
         |        ^
   cc1: some warnings being treated as errors


vim +/folio_memcg +348 mm/workingset.c

   272	
   273	/**
   274	 * workingset_refault - evaluate the refault of a previously evicted folio
   275	 * @page: the freshly allocated replacement folio
   276	 * @shadow: shadow entry of the evicted folio
   277	 *
   278	 * Calculates and evaluates the refault distance of the previously
   279	 * evicted folio in the context of the node and the memcg whose memory
   280	 * pressure caused the eviction.
   281	 */
   282	void workingset_refault(struct folio *folio, void *shadow)
   283	{
   284		bool file = folio_is_file_lru(folio);
   285		struct mem_cgroup *eviction_memcg;
   286		struct lruvec *eviction_lruvec;
   287		unsigned long refault_distance;
   288		unsigned long workingset_size;
   289		struct pglist_data *pgdat;
   290		struct mem_cgroup *memcg;
   291		unsigned long eviction;
   292		struct lruvec *lruvec;
   293		unsigned long refault;
   294		bool workingset;
   295		int memcgid;
   296	
   297		unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset);
   298	
   299		rcu_read_lock();
   300		/*
   301		 * Look up the memcg associated with the stored ID. It might
   302		 * have been deleted since the folio's eviction.
   303		 *
   304		 * Note that in rare events the ID could have been recycled
   305		 * for a new cgroup that refaults a shared folio. This is
   306		 * impossible to tell from the available data. However, this
   307		 * should be a rare and limited disturbance, and activations
   308		 * are always speculative anyway. Ultimately, it's the aging
   309		 * algorithm's job to shake out the minimum access frequency
   310		 * for the active cache.
   311		 *
   312		 * XXX: On !CONFIG_MEMCG, this will always return NULL; it
   313		 * would be better if the root_mem_cgroup existed in all
   314		 * configurations instead.
   315		 */
   316		eviction_memcg = mem_cgroup_from_id(memcgid);
   317		if (!mem_cgroup_disabled() && !eviction_memcg)
   318			goto out;
   319		eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat);
   320		refault = atomic_long_read(&eviction_lruvec->nonresident_age);
   321	
   322		/*
   323		 * Calculate the refault distance
   324		 *
   325		 * The unsigned subtraction here gives an accurate distance
   326		 * across nonresident_age overflows in most cases. There is a
   327		 * special case: usually, shadow entries have a short lifetime
   328		 * and are either refaulted or reclaimed along with the inode
   329		 * before they get too old.  But it is not impossible for the
   330		 * nonresident_age to lap a shadow entry in the field, which
   331		 * can then result in a false small refault distance, leading
   332		 * to a false activation should this old entry actually
   333		 * refault again.  However, earlier kernels used to deactivate
   334		 * unconditionally with *every* reclaim invocation for the
   335		 * longest time, so the occasional inappropriate activation
   336		 * leading to pressure on the active list is not a problem.
   337		 */
   338		refault_distance = (refault - eviction) & EVICTION_MASK;
   339	
   340		/*
   341		 * The activation decision for this folio is made at the level
   342		 * where the eviction occurred, as that is where the LRU order
   343		 * during folio reclaim is being determined.
   344		 *
   345		 * However, the cgroup that will own the folio is the one that
   346		 * is actually experiencing the refault event.
   347		 */
 > 348		memcg = folio_memcg(folio);
   349		lruvec = mem_cgroup_lruvec(memcg, pgdat);
   350	
   351		inc_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file);
   352	
   353		/*
   354		 * Compare the distance to the existing workingset size. We
   355		 * don't activate pages that couldn't stay resident even if
   356		 * all the memory was available to the workingset. Whether
   357		 * workingset competition needs to consider anon or not depends
   358		 * on having swap.
   359		 */
   360		workingset_size = lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE);
   361		if (!file) {
   362			workingset_size += lruvec_page_state(eviction_lruvec,
   363							     NR_INACTIVE_FILE);
   364		}
   365		if (mem_cgroup_get_nr_swap_pages(memcg) > 0) {
   366			workingset_size += lruvec_page_state(eviction_lruvec,
   367							     NR_ACTIVE_ANON);
   368			if (file) {
   369				workingset_size += lruvec_page_state(eviction_lruvec,
   370							     NR_INACTIVE_ANON);
   371			}
   372		}
   373		if (refault_distance > workingset_size)
   374			goto out;
   375	
   376		folio_set_active_flag(folio);
   377		workingset_age_nonresident(lruvec, folio_nr_pages(folio));
   378		inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + file);
   379	
   380		/* Folio was active prior to eviction */
   381		if (workingset) {
   382			folio_set_workingset_flag(folio);
   383			/* XXX: Move to lru_cache_add() when it supports new vs putback */
   384			lru_note_cost_folio(folio);
   385			inc_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + file);
   386		}
   387	out:
   388		rcu_read_unlock();
   389	}
   390	

---
0-DAY CI Kernel Test Service, Intel Corporation
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