[davidhildenbrand:migration 22/22] include/linux/mm.h:2161:47: error: use of undeclared identifier 'PAGE_MAPPING_FLAGS'

[davidhildenbrand:migration 22/22] include/linux/mm.h:2161:47: error: use of undeclared identifier 'PAGE_MAPPING_FLAGS'

[kernel test robot]

tree:   https://github.com/davidhildenbrand/linux migration
head:   e21c02eb687873041b47954e3fc7b47e9d3d3675
commit: e21c02eb687873041b47954e3fc7b47e9d3d3675 [22/22] mm: rename PAGE_MAPPING_* to FOLIO_MAPPING_*
config: arm-randconfig-002-20250514 (https://download.01.org/0day-ci/archive/20250514/202505140705.prYAlYt7-lkp@intel.com/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project f819f46284f2a79790038e1f6649172789734ae8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250514/202505140705.prYAlYt7-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/202505140705.prYAlYt7-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/arm/kernel/asm-offsets.c:12:
>> include/linux/mm.h:2161:47: error: use of undeclared identifier 'PAGE_MAPPING_FLAGS'
    2161 |         } else if (!((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS)) {
         |                                                      ^
   1 error generated.
   make[3]: *** [scripts/Makefile.build:98: arch/arm/kernel/asm-offsets.s] Error 1 shuffle=2209529806
   make[3]: Target 'prepare' not remade because of errors.
   make[2]: *** [Makefile:1275: prepare0] Error 2 shuffle=2209529806
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:248: __sub-make] Error 2 shuffle=2209529806
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:248: __sub-make] Error 2 shuffle=2209529806
   make: Target 'prepare' not remade because of errors.


vim +/PAGE_MAPPING_FLAGS +2161 include/linux/mm.h

fa4e3f5ffa5e6e Vishal Moola (Oracle  2023-01-30  2116) 
e6f83630b79ed4 Shivank Garg          2025-04-30  2117  /**
e6f83630b79ed4 Shivank Garg          2025-04-30  2118   * folio_expected_ref_count - calculate the expected folio refcount
e6f83630b79ed4 Shivank Garg          2025-04-30  2119   * @folio: the folio
e6f83630b79ed4 Shivank Garg          2025-04-30  2120   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2121   * Calculate the expected folio refcount, taking references from the pagecache,
e6f83630b79ed4 Shivank Garg          2025-04-30  2122   * swapcache, PG_private and page table mappings into account. Useful in
e6f83630b79ed4 Shivank Garg          2025-04-30  2123   * combination with folio_ref_count() to detect unexpected references (e.g.,
e6f83630b79ed4 Shivank Garg          2025-04-30  2124   * GUP or other temporary references).
e6f83630b79ed4 Shivank Garg          2025-04-30  2125   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2126   * Does currently not consider references from the LRU cache. If the folio
e6f83630b79ed4 Shivank Garg          2025-04-30  2127   * was isolated from the LRU (which is the case during migration or split),
e6f83630b79ed4 Shivank Garg          2025-04-30  2128   * the LRU cache does not apply.
e6f83630b79ed4 Shivank Garg          2025-04-30  2129   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2130   * Calling this function on an unmapped folio -- !folio_mapped() -- that is
e6f83630b79ed4 Shivank Garg          2025-04-30  2131   * locked will return a stable result.
e6f83630b79ed4 Shivank Garg          2025-04-30  2132   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2133   * Calling this function on a mapped folio will not result in a stable result,
e6f83630b79ed4 Shivank Garg          2025-04-30  2134   * because nothing stops additional page table mappings from coming (e.g.,
e6f83630b79ed4 Shivank Garg          2025-04-30  2135   * fork()) or going (e.g., munmap()).
e6f83630b79ed4 Shivank Garg          2025-04-30  2136   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2137   * Calling this function without the folio lock will also not result in a
e6f83630b79ed4 Shivank Garg          2025-04-30  2138   * stable result: for example, the folio might get dropped from the swapcache
e6f83630b79ed4 Shivank Garg          2025-04-30  2139   * concurrently.
e6f83630b79ed4 Shivank Garg          2025-04-30  2140   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2141   * However, even when called without the folio lock or on a mapped folio,
e6f83630b79ed4 Shivank Garg          2025-04-30  2142   * this function can be used to detect unexpected references early (for example,
e6f83630b79ed4 Shivank Garg          2025-04-30  2143   * if it makes sense to even lock the folio and unmap it).
e6f83630b79ed4 Shivank Garg          2025-04-30  2144   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2145   * The caller must add any reference (e.g., from folio_try_get()) it might be
e6f83630b79ed4 Shivank Garg          2025-04-30  2146   * holding itself to the result.
e6f83630b79ed4 Shivank Garg          2025-04-30  2147   *
e6f83630b79ed4 Shivank Garg          2025-04-30  2148   * Returns the expected folio refcount.
e6f83630b79ed4 Shivank Garg          2025-04-30  2149   */
e6f83630b79ed4 Shivank Garg          2025-04-30  2150  static inline int folio_expected_ref_count(const struct folio *folio)
e6f83630b79ed4 Shivank Garg          2025-04-30  2151  {
e6f83630b79ed4 Shivank Garg          2025-04-30  2152  	const int order = folio_order(folio);
e6f83630b79ed4 Shivank Garg          2025-04-30  2153  	int ref_count = 0;
e6f83630b79ed4 Shivank Garg          2025-04-30  2154  
e6f83630b79ed4 Shivank Garg          2025-04-30  2155  	if (WARN_ON_ONCE(folio_test_slab(folio)))
e6f83630b79ed4 Shivank Garg          2025-04-30  2156  		return 0;
e6f83630b79ed4 Shivank Garg          2025-04-30  2157  
e6f83630b79ed4 Shivank Garg          2025-04-30  2158  	if (folio_test_anon(folio)) {
e6f83630b79ed4 Shivank Garg          2025-04-30  2159  		/* One reference per page from the swapcache. */
e6f83630b79ed4 Shivank Garg          2025-04-30  2160  		ref_count += folio_test_swapcache(folio) << order;
e6f83630b79ed4 Shivank Garg          2025-04-30 @2161  	} else if (!((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS)) {
e6f83630b79ed4 Shivank Garg          2025-04-30  2162  		/* One reference per page from the pagecache. */
e6f83630b79ed4 Shivank Garg          2025-04-30  2163  		ref_count += !!folio->mapping << order;
e6f83630b79ed4 Shivank Garg          2025-04-30  2164  		/* One reference from PG_private. */
e6f83630b79ed4 Shivank Garg          2025-04-30  2165  		ref_count += folio_test_private(folio);
e6f83630b79ed4 Shivank Garg          2025-04-30  2166  	}
e6f83630b79ed4 Shivank Garg          2025-04-30  2167  
e6f83630b79ed4 Shivank Garg          2025-04-30  2168  	/* One reference per page table mapping. */
e6f83630b79ed4 Shivank Garg          2025-04-30  2169  	return ref_count + folio_mapcount(folio);
e6f83630b79ed4 Shivank Garg          2025-04-30  2170  }
e6f83630b79ed4 Shivank Garg          2025-04-30  2171  

:::::: The code at line 2161 was first introduced by commit
:::::: e6f83630b79ed43763cd19a20f80885f568b8991 mm: add folio_expected_ref_count() for reference count calculation

:::::: TO: Shivank Garg <shivankg@amd.com>
:::::: CC: Andrew Morton <akpm@linux-foundation.org>

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