fs/btrfs/inode.o: warning: objtool: wait_subpage_spinlock+0xe4: unreachable instruction

fs/btrfs/inode.o: warning: objtool: wait_subpage_spinlock+0xe4: unreachable instruction

[kernel test robot]

:::::: 
:::::: Manual check reason: "loongarch: unreachable instruction"
:::::: 

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-kernel@vger.kernel.org
TO: Qu Wenruo <wqu@suse.com>
CC: David Sterba <dsterba@suse.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   5723cc3450bccf7f98f227b9723b5c9f6b3af1c5
commit: fcc384be06aa28d246ace6ca38c8d2b8eb4bf5a4 btrfs: require strict data/metadata split for subpage checks
date:   9 weeks ago
:::::: branch date: 10 hours ago
:::::: commit date: 9 weeks ago
config: loongarch-randconfig-001-20250512 (https://download.01.org/0day-ci/archive/20250518/202505181312.TsLbBoZt-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 13.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250518/202505181312.TsLbBoZt-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/r/202505181312.TsLbBoZt-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/pgtable.h:6,
                    from include/asm-generic/io.h:1108,
                    from arch/loongarch/include/asm/io.h:82,
                    from arch/loongarch/include/asm/kasan.h:10,
                    from include/linux/kasan.h:21,
                    from include/linux/slab.h:256,
                    from include/linux/crypto.h:17,
                    from include/crypto/hash.h:12,
                    from fs/btrfs/inode.c:6:
   include/linux/swapops.h: In function 'swp_entry_to_pmd':
   arch/loongarch/include/asm/pgtable.h:303:34: warning: missing braces around initializer [-Wmissing-braces]
     303 | #define __swp_entry_to_pmd(x)   ((pmd_t) { (x).val | _PAGE_HUGE })
         |                                  ^
   include/linux/swapops.h:578:16: note: in expansion of macro '__swp_entry_to_pmd'
     578 |         return __swp_entry_to_pmd(arch_entry);
         |                ^~~~~~~~~~~~~~~~~~
>> fs/btrfs/inode.o: warning: objtool: wait_subpage_spinlock+0xe4: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_add_inode_to_root+0x124: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: insert_inline_extent+0xf8: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_del_delalloc_inode+0x11c: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_set_delalloc_extent+0x258: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_evict_inode+0x3ac: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_get_extent+0x6a4: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_create_io_em+0xd0: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: cow_file_range+0x2e0: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: run_delalloc_nocow+0x2f4: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: compress_file_range+0x258: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_finish_one_ordered+0x638: unreachable instruction
   fs/btrfs/inode.o: warning: objtool: btrfs_invalidate_folio+0x178: unreachable instruction

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