Re: [PATCH V2 4/7] mm: Use pmdp_get() for accessing PMD entries

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

Hi Anshuman,

kernel test robot noticed the following build errors:

[auto build test ERROR on char-misc/char-misc-testing]
[also build test ERROR on char-misc/char-misc-next char-misc/char-misc-linus brauner-vfs/vfs.all dennis-percpu/for-next linus/master v6.11]
[cannot apply to akpm-mm/mm-everything next-20240918]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Anshuman-Khandual/m68k-mm-Change-pmd_val/20240917-153331
base:   char-misc/char-misc-testing
patch link:    https://lore.kernel.org/r/20240917073117.1531207-5-anshuman.khandual%40arm.com
patch subject: [PATCH V2 4/7] mm: Use pmdp_get() for accessing PMD entries
config: um-allnoconfig (https://download.01.org/0day-ci/archive/20240919/202409190205.YJ5gtx3T-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240919/202409190205.YJ5gtx3T-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/202409190205.YJ5gtx3T-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from mm/pgtable-generic.c:10:
   In file included from include/linux/pagemap.h:11:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:5:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:14:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:548:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     548 |         val = __raw_readb(PCI_IOBASE + addr);
         |                           ~~~~~~~~~~ ^
   include/asm-generic/io.h:561:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     561 |         val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
         |                                                         ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
      37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
         |                                                   ^
   In file included from mm/pgtable-generic.c:10:
   In file included from include/linux/pagemap.h:11:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:5:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:14:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     574 |         val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
         |                                                         ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
      35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
         |                                                   ^
   In file included from mm/pgtable-generic.c:10:
   In file included from include/linux/pagemap.h:11:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:5:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:14:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     585 |         __raw_writeb(value, PCI_IOBASE + addr);
         |                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     595 |         __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
         |                                                       ~~~~~~~~~~ ^
   include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     605 |         __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
         |                                                       ~~~~~~~~~~ ^
   include/asm-generic/io.h:693:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     693 |         readsb(PCI_IOBASE + addr, buffer, count);
         |                ~~~~~~~~~~ ^
   include/asm-generic/io.h:701:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     701 |         readsw(PCI_IOBASE + addr, buffer, count);
         |                ~~~~~~~~~~ ^
   include/asm-generic/io.h:709:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     709 |         readsl(PCI_IOBASE + addr, buffer, count);
         |                ~~~~~~~~~~ ^
   include/asm-generic/io.h:718:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     718 |         writesb(PCI_IOBASE + addr, buffer, count);
         |                 ~~~~~~~~~~ ^
   include/asm-generic/io.h:727:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     727 |         writesw(PCI_IOBASE + addr, buffer, count);
         |                 ~~~~~~~~~~ ^
   include/asm-generic/io.h:736:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     736 |         writesl(PCI_IOBASE + addr, buffer, count);
         |                 ~~~~~~~~~~ ^
>> mm/pgtable-generic.c:54:2: error: cannot take the address of an rvalue of type 'pgd_t'
      54 |         pmd_ERROR(pmdp_get(pmd));
         |         ^~~~~~~~~~~~~~~~~~~~~~~~
   include/asm-generic/pgtable-nopmd.h:36:28: note: expanded from macro 'pmd_ERROR'
      36 | #define pmd_ERROR(pmd)                          (pud_ERROR((pmd).pud))
         |                                                  ^~~~~~~~~~~~~~~~~~~~
   include/asm-generic/pgtable-nopud.h:32:28: note: expanded from macro 'pud_ERROR'
      32 | #define pud_ERROR(pud)                          (p4d_ERROR((pud).p4d))
         |                                                  ^~~~~~~~~~~~~~~~~~~~
   include/asm-generic/pgtable-nop4d.h:25:28: note: expanded from macro 'p4d_ERROR'
      25 | #define p4d_ERROR(p4d)                          (pgd_ERROR((p4d).pgd))
         |                                                  ^~~~~~~~~~~~~~~~~~~~
   arch/um/include/asm/pgtable-2level.h:31:67: note: expanded from macro 'pgd_ERROR'
      31 |         printk("%s:%d: bad pgd %p(%08lx).\n", __FILE__, __LINE__, &(e), \
         |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
      32 |                pgd_val(e))
         |                ~~~~~~~~~~~
   include/linux/printk.h:465:60: note: expanded from macro 'printk'
     465 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
         |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
   include/linux/printk.h:437:19: note: expanded from macro 'printk_index_wrap'
     437 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
         |                                 ^~~~~~~~~~~
   12 warnings and 1 error generated.


vim +/pgd_t +54 mm/pgtable-generic.c

    46	
    47	/*
    48	 * Note that the pmd variant below can't be stub'ed out just as for p4d/pud
    49	 * above. pmd folding is special and typically pmd_* macros refer to upper
    50	 * level even when folded
    51	 */
    52	void pmd_clear_bad(pmd_t *pmd)
    53	{
  > 54		pmd_ERROR(pmdp_get(pmd));
    55		pmd_clear(pmd);
    56	}
    57	

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