Re: [PATCH] arm64/hugetlb: Fix building errors in huge_ptep_clear_flush()

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 5/27/2022 3:12 PM, Gavin Shan wrote:
> Hi Baolin,
> 
> On 5/27/22 12:51 PM, Baolin Wang wrote:
>> Fix below building errors which was caused by commit ae07562909f3
>> ("mm: change huge_ptep_clear_flush() to return the original pte")
>> interacting with commit fb396bb459c1 ("arm64/hugetlb: Drop TLB flush
>> from get_clear_flush()").
>>
>> Due to the new get_clear_contig() has dropped TLB flush, we should
>> add an explicit TLB flush in huge_ptep_clear_flush() to keep original
>> semantics when changing to use new get_clear_contig().
>>
>> "
>> arch/arm64/mm/hugetlbpage.c: In function ‘huge_ptep_clear_flush’:
>> arch/arm64/mm/hugetlbpage.c:515:9: error: implicit declaration of
>> function ‘get_clear_flush’; did you mean ‘ptep_clear_flush’?
>> [-Werror=implicit-function-declaration]
>>    515 |  return get_clear_flush(vma->vm_mm, addr, ptep, pgsize, 
>> ncontig);
>>        |         ^~~~~~~~~~~~~~~
>>        |         ptep_clear_flush
>> "
>>
>> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> ---
>>   arch/arm64/mm/hugetlbpage.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
> 
> I ran to the compiling failure either and it would be caused by
> commit fb396bb459c1 ("arm64/hugetlb: Drop TLB flush from 
> get_clear_flush()").
> It's worthy to have a "Fixes" tag. With those fixed:

Thanks for reminding. IMHO, better to add 2 related commits' fix tag. 
Linus, could you help to add them when applying this patch, or need a 
resend? Thanks.

Fixes: ae07562909f3 ("mm: change huge_ptep_clear_flush() to return the 
original pte")
Fixes: fb396bb459c1 ("arm64/hugetlb: Drop TLB flush from 
get_clear_flush()").

> 
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> 
> 
>> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
>> index 0f0c17dfeb9c..e2a5ec9fdc0d 100644
>> --- a/arch/arm64/mm/hugetlbpage.c
>> +++ b/arch/arm64/mm/hugetlbpage.c
>> @@ -507,12 +507,15 @@ pte_t huge_ptep_clear_flush(struct 
>> vm_area_struct *vma,
>>   {
>>       size_t pgsize;
>>       int ncontig;
>> +    pte_t orig_pte;
>>       if (!pte_cont(READ_ONCE(*ptep)))
>>           return ptep_clear_flush(vma, addr, ptep);
>>       ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
>> -    return get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
>> +    orig_pte = get_clear_contig(vma->vm_mm, addr, ptep, pgsize, 
>> ncontig);
>> +    flush_tlb_range(vma, addr, addr + pgsize * ncontig);
>> +    return orig_pte;
>>   }
>>   static int __init hugetlbpage_init(void)
>>
> 
> Thanks,
> Gavin

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