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Date:   Tue, 19 Sep 2023 18:42:19 +0800
From:   kernel test robot <lkp@intel.com>
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org,
        Alexander Larsson <alexl@redhat.com>,
        Miklos Szeredi <mszeredi@redhat.com>
Subject: arch/alpha/include/asm/rwonce.h:25:35: warning: array subscript 0 is
 outside array bounds of 'struct inode[11885788707287082]'
Message-ID: <202309191848.cMwd2D4d-lkp@intel.com>
MIME-Version: 1.0
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Precedence: bulk

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   2cf0f715623872823a72e451243bbf555d10d032
commit: 0af950f57fefabab628f1963af881e6b9bfe7f38 ovl: move ovl_entry into ovl_inode
date:   3 months ago
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20230919/202309191848.cMwd2D4d-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230919/202309191848.cMwd2D4d-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/202309191848.cMwd2D4d-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/compiler.h:246,
                    from include/linux/build_bug.h:5,
                    from include/linux/container_of.h:5,
                    from include/linux/list.h:5,
                    from include/linux/wait.h:7,
                    from include/linux/wait_bit.h:8,
                    from include/linux/fs.h:6,
                    from fs/overlayfs/util.c:7:
   In function 'ovl_upperdentry_dereference',
       inlined from 'ovl_dentry_upper' at fs/overlayfs/util.c:266:9,
       inlined from 'ovl_path_type' at fs/overlayfs/util.c:184:6:
>> arch/alpha/include/asm/rwonce.h:25:35: warning: array subscript 0 is outside array bounds of 'struct inode[11885788707287082]' [-Warray-bounds=]
      25 |         __unqual_scalar_typeof(x) __x =                                 \
         |                                   ^~~
   include/asm-generic/rwonce.h:50:9: note: in expansion of macro '__READ_ONCE'
      50 |         __READ_ONCE(x);                                                 \
         |         ^~~~~~~~~~~
   fs/overlayfs/ovl_entry.h:163:16: note: in expansion of macro 'READ_ONCE'
     163 |         return READ_ONCE(oi->__upperdentry);
         |                ^~~~~~~~~


vim +25 arch/alpha/include/asm/rwonce.h

d6462858851549 Will Deacon 2019-10-30  11  
d6462858851549 Will Deacon 2019-10-30  12  /*
d6462858851549 Will Deacon 2019-10-30  13   * Alpha is apparently daft enough to reorder address-dependent loads
d6462858851549 Will Deacon 2019-10-30  14   * on some CPU implementations. Knock some common sense into it with
d6462858851549 Will Deacon 2019-10-30  15   * a memory barrier in READ_ONCE().
d6462858851549 Will Deacon 2019-10-30  16   *
d6462858851549 Will Deacon 2019-10-30  17   * For the curious, more information about this unusual reordering is
d6462858851549 Will Deacon 2019-10-30  18   * available in chapter 15 of the "perfbook":
d6462858851549 Will Deacon 2019-10-30  19   *
d6462858851549 Will Deacon 2019-10-30  20   *  https://kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.html
d6462858851549 Will Deacon 2019-10-30  21   *
d6462858851549 Will Deacon 2019-10-30  22   */
d6462858851549 Will Deacon 2019-10-30  23  #define __READ_ONCE(x)							\
d6462858851549 Will Deacon 2019-10-30  24  ({									\
d6462858851549 Will Deacon 2019-10-30 @25  	__unqual_scalar_typeof(x) __x =					\
d6462858851549 Will Deacon 2019-10-30  26  		(*(volatile typeof(__x) *)(&(x)));			\
d6462858851549 Will Deacon 2019-10-30  27  	mb();								\
d6462858851549 Will Deacon 2019-10-30  28  	(typeof(x))__x;							\
d6462858851549 Will Deacon 2019-10-30  29  })
d6462858851549 Will Deacon 2019-10-30  30  

:::::: The code at line 25 was first introduced by commit
:::::: d6462858851549c62d73eaa14b31132b0f32d6b6 alpha: Override READ_ONCE() with barriered implementation

:::::: TO: Will Deacon <will@kernel.org>
:::::: CC: Will Deacon <will@kernel.org>

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