Re: [PATCH] mm: Fix shmem THP counters on migration

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

Hi Jan,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Jan-Glauber/mm-Fix-shmem-THP-counters-on-migration/20230619-135947
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230619055735.141740-1-jglauber%40digitalocean.com
patch subject: [PATCH] mm: Fix shmem THP counters on migration
config: sparc-randconfig-r024-20230619 (https://download.01.org/0day-ci/archive/20230619/202306191545.gATleHf1-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230619/202306191545.gATleHf1-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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306191545.gATleHf1-lkp@intel.com/

All errors (new ones prefixed by >>):

   mm/migrate.c: In function 'folio_migrate_mapping':
>> mm/migrate.c:491:64: error: 'NR_SHMEM_THP' undeclared (first use in this function); did you mean 'NR_SHMEM_THPS'?
     491 |                                 __mod_lruvec_state(old_lruvec, NR_SHMEM_THP, -nr);
         |                                                                ^~~~~~~~~~~~
         |                                                                NR_SHMEM_THPS
   mm/migrate.c:491:64: note: each undeclared identifier is reported only once for each function it appears in


vim +491 mm/migrate.c

   389	
   390	/*
   391	 * Replace the page in the mapping.
   392	 *
   393	 * The number of remaining references must be:
   394	 * 1 for anonymous pages without a mapping
   395	 * 2 for pages with a mapping
   396	 * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
   397	 */
   398	int folio_migrate_mapping(struct address_space *mapping,
   399			struct folio *newfolio, struct folio *folio, int extra_count)
   400	{
   401		XA_STATE(xas, &mapping->i_pages, folio_index(folio));
   402		struct zone *oldzone, *newzone;
   403		int dirty;
   404		int expected_count = folio_expected_refs(mapping, folio) + extra_count;
   405		long nr = folio_nr_pages(folio);
   406	
   407		if (!mapping) {
   408			/* Anonymous page without mapping */
   409			if (folio_ref_count(folio) != expected_count)
   410				return -EAGAIN;
   411	
   412			/* No turning back from here */
   413			newfolio->index = folio->index;
   414			newfolio->mapping = folio->mapping;
   415			if (folio_test_swapbacked(folio))
   416				__folio_set_swapbacked(newfolio);
   417	
   418			return MIGRATEPAGE_SUCCESS;
   419		}
   420	
   421		oldzone = folio_zone(folio);
   422		newzone = folio_zone(newfolio);
   423	
   424		xas_lock_irq(&xas);
   425		if (!folio_ref_freeze(folio, expected_count)) {
   426			xas_unlock_irq(&xas);
   427			return -EAGAIN;
   428		}
   429	
   430		/*
   431		 * Now we know that no one else is looking at the folio:
   432		 * no turning back from here.
   433		 */
   434		newfolio->index = folio->index;
   435		newfolio->mapping = folio->mapping;
   436		folio_ref_add(newfolio, nr); /* add cache reference */
   437		if (folio_test_swapbacked(folio)) {
   438			__folio_set_swapbacked(newfolio);
   439			if (folio_test_swapcache(folio)) {
   440				folio_set_swapcache(newfolio);
   441				newfolio->private = folio_get_private(folio);
   442			}
   443		} else {
   444			VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
   445		}
   446	
   447		/* Move dirty while page refs frozen and newpage not yet exposed */
   448		dirty = folio_test_dirty(folio);
   449		if (dirty) {
   450			folio_clear_dirty(folio);
   451			folio_set_dirty(newfolio);
   452		}
   453	
   454		xas_store(&xas, newfolio);
   455	
   456		/*
   457		 * Drop cache reference from old page by unfreezing
   458		 * to one less reference.
   459		 * We know this isn't the last reference.
   460		 */
   461		folio_ref_unfreeze(folio, expected_count - nr);
   462	
   463		xas_unlock(&xas);
   464		/* Leave irq disabled to prevent preemption while updating stats */
   465	
   466		/*
   467		 * If moved to a different zone then also account
   468		 * the page for that zone. Other VM counters will be
   469		 * taken care of when we establish references to the
   470		 * new page and drop references to the old page.
   471		 *
   472		 * Note that anonymous pages are accounted for
   473		 * via NR_FILE_PAGES and NR_ANON_MAPPED if they
   474		 * are mapped to swap space.
   475		 */
   476		if (newzone != oldzone) {
   477			struct lruvec *old_lruvec, *new_lruvec;
   478			struct mem_cgroup *memcg;
   479	
   480			memcg = folio_memcg(folio);
   481			old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
   482			new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);
   483	
   484			__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
   485			__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
   486			if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
   487				__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
   488				__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
   489	
   490				if (folio_test_transhuge(folio)) {
 > 491					__mod_lruvec_state(old_lruvec, NR_SHMEM_THP, -nr);
   492					__mod_lruvec_state(new_lruvec, NR_SHMEM_THP, nr);
   493				}
   494			}
   495	#ifdef CONFIG_SWAP
   496			if (folio_test_swapcache(folio)) {
   497				__mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
   498				__mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
   499			}
   500	#endif
   501			if (dirty && mapping_can_writeback(mapping)) {
   502				__mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
   503				__mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
   504				__mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
   505				__mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
   506			}
   507		}
   508		local_irq_enable();
   509	
   510		return MIGRATEPAGE_SUCCESS;
   511	}
   512	EXPORT_SYMBOL(folio_migrate_mapping);
   513	

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https://github.com/intel/lkp-tests/wiki