Re: [PATCH V13] mm/debug: Add tests validating architecture page table helpers
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
> > > 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
> > > > >
> > > > > 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.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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___
Re: [PATCH V13] mm/debug: Add tests validating architecture page table helpers
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
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
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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Re: [PATCH V13] mm/debug: Add tests validating architecture page table helpers
On Mon, Feb 10, 2020 at 11:46:23AM +0100, Christophe Leroy wrote:
>
>
> 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
> > > > > 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
> > > > > > >
> > > > > > > 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
>
Re: [PATCH V12] mm/debug: Add tests validating architecture page table helpers
On Tue, Jan 28, 2020 at 06:57:53AM +0530, Anshuman Khandual wrote:
> This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with
> CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to
> select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and
> arm64. Going forward, other architectures too can enable this after fixing
> build or runtime problems (if any) with their page table helpers.
It may be worth posting the next version to linux-arch to reach out to
other arch maintainers.
Also I've seen that you posted a v13 but it hasn't reached
linux-arm-kernel (likely held in moderation because of the large amount
of addresses cc'ed) and I don't normally follow LKML. I'm not cc'ed to
this patch either (which is fine as long as you post to a list that I
read).
Since I started the reply on v12 about a week ago, I'll follow up here.
When you post a v14, please trim the people on cc only to those strictly
necessary (e.g. arch maintainers, linux-mm, linux-arch and lkml).
> diff --git a/Documentation/features/debug/debug-vm-pgtable/arch-support.txt
> b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt
> new file mode 100644
> index ..f3f8111edbe3
> --- /dev/null
> +++ b/Documentation/features/debug/debug-vm-pgtable/arch-support.txt
> @@ -0,0 +1,35 @@
> +#
> +# Feature name: debug-vm-pgtable
> +# Kconfig: ARCH_HAS_DEBUG_VM_PGTABLE
> +# description: arch supports pgtable tests for semantics compliance
> +#
> +---
> +| arch |status|
> +---
> +| alpha: | TODO |
> +| arc: | ok |
> +| arm: | TODO |
I'm sure you can find some arm32 hardware around (or a VM) to give this
a try ;).
> diff --git a/arch/x86/include/asm/pgtable_64.h
> b/arch/x86/include/asm/pgtable_64.h
> index 0b6c4042942a..fb0e76d254b3 100644
> --- a/arch/x86/include/asm/pgtable_64.h
> +++ b/arch/x86/include/asm/pgtable_64.h
[...]
> @@ -1197,6 +1197,7 @@ static noinline void __init kernel_init_freeable(void)
> sched_init_smp();
>
> page_alloc_init_late();
> + debug_vm_pgtable();
> /* Initialize page ext after all struct pages are initialized. */
> page_ext_init();
I guess you could even make debug_vm_pgtable() an early_initcall(). I
don't have a strong opinion either way.
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> new file mode 100644
> index ..0f37f32d15f1
> --- /dev/null
> +++ b/mm/debug_vm_pgtable.c
> @@ -0,0 +1,388 @@
[...]
> +/*
> + * Basic operations
> + *
> + * mkold(entry) = An old and not a young entry
> + * mkyoung(entry)= A young and not an old entry
> + * mkdirty(entry)= A dirty and not a clean entry
> + * mkclean(entry)= A clean and not a dirty entry
> + * mkwrite(entry)= A write and not a write protected entry
> + * wrprotect(entry) = A write protected and not a write entry
> + * pxx_bad(entry)= A mapped and non-table entry
> + * pxx_same(entry1, entry2) = Both entries hold the exact same value
> + */
> +#define VMFLAGS (VM_READ|VM_WRITE|VM_EXEC)
> +
> +/*
> + * On s390 platform, the lower 12 bits are used to identify given page table
> + * entry type and for other arch specific requirements. But these bits might
> + * affect the ability to clear entries with pxx_clear(). So while loading up
> + * the entries skip all lower 12 bits in order to accommodate s390 platform.
> + * It does not have affect any other platform.
> + */
> +#define RANDOM_ORVALUE (0xf000UL)
I'd suggest you generate this mask with something like
GENMASK(BITS_PER_LONG, PAGE_SHIFT).
> +#define RANDOM_NZVALUE (0xff)
> +
> +static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
> +{
> + pte_t pte = pfn_pte(pfn, prot);
> +
> + WARN_ON(!pte_same(pte, pte));
> + WARN_ON(!pte_young(pte_mkyoung(pte)));
> + WARN_ON(!pte_dirty(pte_mkdirty(pte)));
> + WARN_ON(!pte_write(pte_mkwrite(pte)));
> + WARN_ON(pte_young(pte_mkold(pte)));
> + WARN_ON(pte_dirty(pte_mkclean(pte)));
> + WARN_ON(pte_write(pte_wrprotect(pte)));
Given that you start with rwx permissions set,
some of these ops would not have any effect. For example, on arm64 at
least, mkwrite clears a bit already cleared here. You could try with
multiple rwx combinations values (e.g. all set and all cleared) or maybe
something like below:
WARN_ON(!pte_write(pte_mkwrite(pte_wrprotect(pte;
You could also try something like this:
WARN_ON(!pte_same(pte_wrprotect(pte), pte_wrprotect(pte_mkwrite(pte;
though the above approach may not work for arm64 ptep_set_wrprotect() on
a dirty pte (if you extend these tests later).
> +}
> +
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
> +{
> + pmd_t pmd = pfn_pmd(pfn, pr
Re: [PATCH V13] mm/debug: Add tests validating architecture page table helpers
On 02/10/2020 04:36 PM, Russell King - ARM Linux admin wrote:
> On Mon, Feb 10, 2020 at 11:46:23AM +0100, Christophe Leroy wrote:
>>
>>
>> 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
>> 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
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, th
Re: [PATCH V13] mm/debug: Add tests validating architecture page table helpers
Le 11/02/2020 à 03:25, Anshuman Khandual a écrit : On 02/10/2020 04:36 PM, Russell King - ARM Linux admin wrote: There are good reasons for the way ARM does stuff. The generic crap was written without regard for the circumstances that ARM has, and thus is entirely unsuitable for 32-bit ARM. Since we dont have an agreement here, lets just settle with disabling the test for now on platforms where the build fails. CONFIG_EXPERT is enabling this test for better adaptability and coverage, hence how about re framing the config like this ? This at the least conveys the fact that EXPERT only works when platform is neither IA64 or ARM. Agreed config DEBUG_VM_PGTABLE bool "Debug arch page table for semantics compliance" depends on MMU depends on ARCH_HAS_DEBUG_VM_PGTABLE || (EXPERT && !(IA64 || ARM)) I think it's maybe better to have a dedicated depends line: depends on !IA64 && !ARM depends on ARCH_HAS_DEBUG_VM_PGTABLE || EXPERT The day arm and/or ia64 is ready for building the test, we can remove that depends. default n if !ARCH_HAS_DEBUG_VM_PGTABLE default y if DEBUG_VM Christophe ___ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc
