Le 10/02/2020 à 11:02, Russell King - ARM Linux admin a écrit : > On Mon, Feb 10, 2020 at 07:38:38AM +0100, Christophe Leroy wrote: >> >> >> Le 10/02/2020 à 06:35, Anshuman Khandual a écrit : >>> >>> >>> On 02/10/2020 10:22 AM, Andrew Morton wrote: >>>> On Thu, 6 Feb 2020 13:49:35 +0530 Anshuman Khandual <anshu****@arm*****> wrote: >>>> >>>>> >>>>> On 02/06/2020 04:40 AM, kbuild test robot wrote: >>>>>> Hi Anshuman, >>>>>> >>>>>> Thank you for the patch! Yet something to improve: >>>>>> >>>>>> [auto build test ERROR on powerpc/next] >>>>>> [also build test ERROR on s390/features linus/master arc/for-next v5.5] >>>>>> [cannot apply to mmotm/master tip/x86/core arm64/for-next/core next-20200205] >>>>>> [if your patch is applied to the wrong git tree, please drop us a note to help >>>>>> improve the system. BTW, we also suggest to use '--base' option to specify the >>>>>> base tree in git format-patch, please see https://stackoverflow.com/a/37406982] >>>>>> >>>>>> url: https://github.com/0day-ci/linux/commits/Anshuman-Khandual/mm-debug-Add-tests-validating-architecture-page-table-helpers/20200205-215507 >>>>>> base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next >>>>>> config: ia64-allmodconfig (attached as .config) >>>>>> compiler: ia64-linux-gcc (GCC) 7.5.0 >>>>>> reproduce: >>>>>> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross >>>>>> chmod +x ~/bin/make.cross >>>>>> # save the attached .config to linux build tree >>>>>> GCC_VERSION=7.5.0 make.cross ARCH=ia64 >>>>>> >>>>>> If you fix the issue, kindly add following tag >>>>>> Reported-by: kbuild test robot <lkp****@intel*****> >>>>>> >>>>>> All error/warnings (new ones prefixed by >>): >>>>>> >>>>>> In file included from include/asm-generic/pgtable-nopud.h:8:0, >>>>>> from arch/ia64/include/asm/pgtable.h:586, >>>>>> from include/linux/mm.h:99, >>>>>> from include/linux/highmem.h:8, >>>>>> from mm/debug_vm_pgtable.c:14: >>>>>> mm/debug_vm_pgtable.c: In function 'pud_clear_tests': >>>>>>>> include/asm-generic/pgtable-nop4d-hack.h:47:32: error: implicit declaration of function '__pgd'; did you mean '__p4d'? [-Werror=implicit-function-declaration] >>>>>> #define __pud(x) ((pud_t) { __pgd(x) }) >>>>>> ^ >>>>>>>> mm/debug_vm_pgtable.c:141:8: note: in expansion of macro '__pud' >>>>>> pud = __pud(pud_val(pud) | RANDOM_ORVALUE); >>>>>> ^~~~~ >>>>>>>> include/asm-generic/pgtable-nop4d-hack.h:47:22: warning: missing braces around initializer [-Wmissing-braces] >>>>>> #define __pud(x) ((pud_t) { __pgd(x) }) >>>>>> ^ >>>>>>>> mm/debug_vm_pgtable.c:141:8: note: in expansion of macro '__pud' >>>>>> pud = __pud(pud_val(pud) | RANDOM_ORVALUE); >>>>>> ^~~~~ >>>>>> cc1: some warnings being treated as errors >>>>> >>>>> This build failure is expected now given that we have allowed DEBUG_VM_PGTABLE >>>>> with EXPERT without platform requiring ARCH_HAS_DEBUG_VM_PGTABLE. This problem >>>>> i.e build failure caused without a platform __pgd(), is known to exist both on >>>>> ia64 and arm (32bit) platforms. Please refer https://lkml.org/lkml/2019/9/24/314 >>>>> for details where this was discussed earlier. >>>>> >>>> >>>> I'd prefer not to merge a patch which is known to cause build >>>> regressions. Is there some temporary thing we can do to prevent these >>>> errors until arch maintainers(?) get around to implementing the >>>> long-term fixes? >>> >>> We could explicitly disable CONFIG_DEBUG_VM_PGTABLE on ia64 and arm platforms >>> which will ensure that others can still use the EXPERT path. >>> >>> config DEBUG_VM_PGTABLE >>> bool "Debug arch page table for semantics compliance" >>> depends on MMU >>> depends on !(IA64 || ARM) >>> depends on ARCH_HAS_DEBUG_VM_PGTABLE || EXPERT >>> default n if !ARCH_HAS_DEBUG_VM_PGTABLE >>> default y if DEBUG_VM >>> >> >> On both ia32 and arm, the fix is trivial. >> >> Can we include the fix within this patch, just the same way as the >> mm_p4d_folded() fix for x86 ? > > Why should arm include a macro for something that nothing (apart from > this checker) requires? If the checker requires it but the rest of > the kernel does not, it suggests that the checker isn't actually > correct, and the results can't be relied upon. > As far as I can see, the problem is that arm opencodes part of the API instead of including asm-generic/pgtable-nopmd.h Here, the ARM has 2 levels, ie only PGD and PTE. But instead of defining __pgd and __pte and getting everything else from asm-generic, it defines a __pmd then redefines the folded levels like the pud, etc ... That's exactly what the checker aims at detecting: architectures than do not properly use the standard linux page table structures. Christophe
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