[android-common:android17-6.18 8/8] mm/gcma.c:459:9: sparse: sparse: Using plain integer as NULL pointer

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

tree:   https://android.googlesource.com/kernel/common android17-6.18
head:   0ded20fe17312e3beb85ae8d0d95984036fe32cd
commit: 5019ce82e0f28db9c8d3a45e77b3efcafb366bbd [8/8] ANDROID: mm: introduce GCMA
config: arm64-randconfig-r2304-20261104 (https://download.01.org/0day-ci/archive/20261104/202611042335.Ib92ULSO-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 15.3.0
sparse: v0.6.5-rc1-21-g84ec0658
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261104/202611042335.Ib92ULSO-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/202611042335.Ib92ULSO-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> mm/gcma.c:459:9: sparse: sparse: Using plain integer as NULL pointer
>> mm/gcma.c:995:23: sparse: sparse: symbol 'gcma_cleancache_ops' was not declared. Should it be static?
   mm/gcma.c:321:13: sparse: sparse: context imbalance in 'page_area_lock' - wrong count at exit
   mm/gcma.c:331:13: sparse: sparse: context imbalance in 'page_area_unlock' - unexpected unlock

vim +459 mm/gcma.c

   449	
   450	static void gcma_erase_page(struct gcma_inode *inode, unsigned long index,
   451				    struct page *page, bool put_page)
   452	{
   453		void *old;
   454	
   455		lockdep_assert_held(&inode->pages.xa_lock);
   456	
   457		/* The inode refcount will decrease when the page is freed */
   458		old = __xa_erase(&inode->pages, index);
 > 459		VM_BUG_ON(old == 0);
   460		delete_page_from_lru(page);
   461		if (put_page)
   462			gcma_put_page(page);
   463	
   464		check_and_remove_inode(inode);
   465	}
   466	

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