[linux-next:master 6546/9925] arch/loongarch/include/asm/cmpxchg.h:70:42: sparse: sparse: cast truncates bits from constant value (8000000000000000 becomes 0)

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   39676dfe52331dba909c617f213fdb21015c8d10
commit: 4a0d72ea10ce156eb2269358fa38528f62a96081 [6546/9925] afs: Overhaul invalidation handling to better support RO volumes
config: loongarch-randconfig-r122-20231229 (https://download.01.org/0day-ci/archive/20231230/202312300218.jKdzoA8z-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 13.2.0
reproduce: (https://download.01.org/0day-ci/archive/20231230/202312300218.jKdzoA8z-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/202312300218.jKdzoA8z-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   fs/afs/callback.c: note: in included file (through include/linux/mmzone.h, include/linux/gfp.h, include/linux/umh.h, include/linux/kmod.h, ...):
   include/linux/page-flags.h:242:46: sparse: sparse: self-comparison always evaluates to false
   fs/afs/callback.c: note: in included file (through arch/loongarch/include/asm/atomic.h, include/linux/atomic.h, include/asm-generic/bitops/atomic.h, ...):
>> arch/loongarch/include/asm/cmpxchg.h:70:42: sparse: sparse: cast truncates bits from constant value (8000000000000000 becomes 0)
   arch/loongarch/include/asm/cmpxchg.h:73:24: sparse: sparse: cast truncates bits from constant value (8000000000000000 becomes 0)
   fs/afs/callback.c:146:22: sparse: sparse: context imbalance in 'afs_lookup_volume_rcu' - different lock contexts for basic block
--
   fs/afs/rotate.c: note: in included file (through include/linux/mmzone.h, include/linux/gfp.h, include/linux/slab.h):
   include/linux/page-flags.h:242:46: sparse: sparse: self-comparison always evaluates to false
   fs/afs/rotate.c: note: in included file (through arch/loongarch/include/asm/atomic.h, include/linux/atomic.h, include/asm-generic/bitops/atomic.h, ...):
>> arch/loongarch/include/asm/cmpxchg.h:70:42: sparse: sparse: cast truncates bits from constant value (8000000000000000 becomes 0)
   arch/loongarch/include/asm/cmpxchg.h:73:24: sparse: sparse: cast truncates bits from constant value (8000000000000000 becomes 0)
   fs/afs/rotate.c:639:42: sparse: sparse: self-comparison always evaluates to true

vim +70 arch/loongarch/include/asm/cmpxchg.h

720dc7ab252bbd Huacai Chen   2022-08-25  63  
ddf502717da029 Huacai Chen   2022-10-12  64  static __always_inline unsigned long
068550631fbe0b Andrzej Hajda 2023-01-18  65  __arch_xchg(volatile void *ptr, unsigned long x, int size)
5b0b14e550a006 Huacai Chen   2022-05-31  66  {
5b0b14e550a006 Huacai Chen   2022-05-31  67  	switch (size) {
720dc7ab252bbd Huacai Chen   2022-08-25  68  	case 1:
720dc7ab252bbd Huacai Chen   2022-08-25  69  	case 2:
720dc7ab252bbd Huacai Chen   2022-08-25 @70  		return __xchg_small(ptr, x, size);
720dc7ab252bbd Huacai Chen   2022-08-25  71  
5b0b14e550a006 Huacai Chen   2022-05-31  72  	case 4:
5b0b14e550a006 Huacai Chen   2022-05-31  73  		return __xchg_asm("amswap_db.w", (volatile u32 *)ptr, (u32)x);
5b0b14e550a006 Huacai Chen   2022-05-31  74  
5b0b14e550a006 Huacai Chen   2022-05-31  75  	case 8:
5b0b14e550a006 Huacai Chen   2022-05-31  76  		return __xchg_asm("amswap_db.d", (volatile u64 *)ptr, (u64)x);
5b0b14e550a006 Huacai Chen   2022-05-31  77  
5b0b14e550a006 Huacai Chen   2022-05-31  78  	default:
5b0b14e550a006 Huacai Chen   2022-05-31  79  		BUILD_BUG();
5b0b14e550a006 Huacai Chen   2022-05-31  80  	}
5b0b14e550a006 Huacai Chen   2022-05-31  81  
5b0b14e550a006 Huacai Chen   2022-05-31  82  	return 0;
5b0b14e550a006 Huacai Chen   2022-05-31  83  }
5b0b14e550a006 Huacai Chen   2022-05-31  84  

:::::: The code at line 70 was first introduced by commit
:::::: 720dc7ab252bbdf404cab7b909e26b31e602bf7e LoongArch: Add subword xchg/cmpxchg emulation

:::::: TO: Huacai Chen <chenhuacai@loongson.cn>
:::::: CC: Huacai Chen <chenhuacai@loongson.cn>

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