[linyunsheng:page_frag_cache_v5 14/14] mm/page_frag_cache.c:291:24: warning: variable 'remaining' is uninitialized when used here

[linyunsheng:page_frag_cache_v5 14/14] mm/page_frag_cache.c:291:24: warning: variable 'remaining' is uninitialized when used here

[kernel test robot]

tree:   https://github.com/gestionlin/linux.git page_frag_cache_v5
head:   e6543161a8d13e28e244803a755a007021b9dea7
commit: e6543161a8d13e28e244803a755a007021b9dea7 [14/14] add alloc_pg api and refactor alloc_va api
config: arm-clps711x_defconfig (https://download.01.org/0day-ci/archive/20240518/202405182348.NZ2WqUhQ-lkp@intel.com/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project fa9b1be45088dce1e4b602d451f118128b94237b)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240518/202405182348.NZ2WqUhQ-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/202405182348.NZ2WqUhQ-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from mm/page_frag_cache.c:17:
   In file included from include/linux/mm.h:2210:
   include/linux/vmstat.h:522:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     522 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
   mm/page_frag_cache.c:289:15: warning: unused variable 'page' [-Wunused-variable]
     289 |         struct page *page;
         |                      ^~~~
>> mm/page_frag_cache.c:291:24: warning: variable 'remaining' is uninitialized when used here [-Wuninitialized]
     291 |         if (unlikely(fragsz > remaining)) {
         |                               ^~~~~~~~~
   include/linux/compiler.h:77:42: note: expanded from macro 'unlikely'
      77 | # define unlikely(x)    __builtin_expect(!!(x), 0)
         |                                             ^
   mm/page_frag_cache.c:288:24: note: initialize the variable 'remaining' to silence this warning
     288 |         unsigned int remaining;
         |                               ^
         |                                = 0
   3 warnings generated.


vim +/remaining +291 mm/page_frag_cache.c

   269	
   270	/**
   271	 * __page_frag_alloc_va_align() - Alloc a page fragment with aligning
   272	 * requirement.
   273	 * @nc: page_frag cache from which to allocate
   274	 * @fragsz: the requested fragment size
   275	 * @gfp_mask: the allocation gfp to use when cache need to be refilled
   276	 * @align_mask: the requested aligning requirement for the 'va'
   277	 *
   278	 * Get a page fragment from page_frag cache with aligning requirement.
   279	 *
   280	 * Return:
   281	 * Return va of the page fragment, otherwise return NULL.
   282	 */
   283	void *__page_frag_alloc_va_align(struct page_frag_cache *nc,
   284					 unsigned int fragsz, gfp_t gfp_mask,
   285					 unsigned int align_mask)
   286	{
   287		struct encoded_va *encoded_va;
   288		unsigned int remaining;
   289		struct page *page;
   290	
 > 291		if (unlikely(fragsz > remaining)) {
   292			/* fragsz is not supposed to be bigger than PAGE_SIZE as we are
   293			 * allowing order 3 page allocation to fail easily under low
   294			 * memory condition.
   295			 */
   296			if (WARN_ON_ONCE(fragsz > PAGE_SIZE) ||
   297			    unlikely(!page_frag_cache_refill(nc, gfp_mask)))
   298				return NULL;
   299		}
   300	
   301		encoded_va = nc->encoded_va;
   302		remaining = nc->remaining & align_mask;
   303		nc->remaining = remaining - fragsz;
   304		nc->pagecnt_bias--;
   305	
   306		return encoded_page_address(encoded_va) +
   307			__page_frag_cache_page_offset(encoded_va, remaining);
   308	}
   309	EXPORT_SYMBOL(__page_frag_alloc_va_align);
   310	

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