linux-kernel - Re: [PATCH V2 0/3] mm/debug: Add more arch page table helper tests

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Message-ID: <ef28cb75-40b8-5ab5-83ba-84fd4384c7c5@c-s.fr>
Date:   Fri, 27 Mar 2020 07:00:45 +0000
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org
Cc:     Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Vineet Gupta <vgupta@...opsys.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-riscv@...ts.infradead.org, x86@...nel.org,
        linux-doc@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 0/3] mm/debug: Add more arch page table helper tests



On 03/27/2020 06:46 AM, Anshuman Khandual wrote:
> 
> On 03/26/2020 08:53 PM, Christophe Leroy wrote:
>>
>>
>> Le 26/03/2020 à 03:23, Anshuman Khandual a écrit :
>>>
>>>
>>> On 03/24/2020 10:52 AM, Anshuman Khandual wrote:
>>>> This series adds more arch page table helper tests. The new tests here are
>>>> either related to core memory functions and advanced arch pgtable helpers.
>>>> This also creates a documentation file enlisting all expected semantics as
>>>> suggested by Mike Rapoport (https://lkml.org/lkml/2020/1/30/40).
>>>>
>>>> This series has been tested on arm64 and x86 platforms.
>>>
>>> If folks can test these patches out on remaining ARCH_HAS_DEBUG_VM_PGTABLE
>>> enabled platforms i.e s390, arc, powerpc (32 and 64), that will be really
>>> appreciated. Thank you.
>>>
>>
>> On powerpc 8xx (PPC32), I get:
>>
>> [   53.338368] debug_vm_pgtable: debug_vm_pgtable: Validating architecture page table helpers
>> [   53.347403] ------------[ cut here ]------------
>> [   53.351832] WARNING: CPU: 0 PID: 1 at mm/debug_vm_pgtable.c:647 debug_vm_pgtable+0x280/0x3f4
> 
> mm/debug_vm_pgtable.c:647 ?
> 
> With the following commits in place
> 
> 53a8338ce (HEAD) Documentation/mm: Add descriptions for arch page table helper
> 5d4913fc1 mm/debug: Add tests validating arch advanced page table helpers
> bcaf120a7 mm/debug: Add tests validating arch page table helpers for core features
> d6ed5a4a5 x86/memory: Drop pud_mknotpresent()
> 0739d1f8d mm/debug: Add tests validating architecture page table helpers
> 16fbf79b0 (tag: v5.6-rc7) Linux 5.6-rc7

I have:

facaa5eb5909 (HEAD -> helpers0) mm/debug: Add tests validating arch 
advanced page table helpers
6389fed515fc mm/debug: Add tests validating arch page table helpers for 
core features
dc14ecc8b94e mm/debug: add tests validating architecture page table helpers
c6624071c338 (origin/merge, merge) Automatic merge of branches 'master', 
'next' and 'fixes' into merge
58e05c5508e6 Automatic merge of branches 'master', 'next' and 'fixes' 
into merge
1b649e0bcae7 (origin/master, origin/HEAD) Merge 
git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

origin is https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git

I can't see your last patch in powerpc mailing list 
(https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=166237)

> 
> mm/debug_vm_pgtable.c:647 is here.

Line 647 is:

	WARN_ON(!pte_same(pte, __swp_entry_to_pte(swp)));


> 
> #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
> static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot)
> {
>          swp_entry_t swp;
>          pmd_t pmd;  -----------------------------> Line #647
> 
>          pmd = pfn_pmd(pfn, prot);
>          swp = __pmd_to_swp_entry(pmd);
>          WARN_ON(!pmd_same(pmd, __swp_entry_to_pmd(swp)));
> }
> #else
> static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot) { }
> #end
> 
> Did I miss something ?
> 

[...]

> Could you please point me to the exact test which is failing ?
> 
>> [   53.519778] Freeing unused kernel memory: 608K
>>
>>
> So I assume that the system should have come till runtime just fine apart from
> the above warning message because.
> 

Yes it boots fine otherwise.

Christophe