On 11/03/2016 03:15 AM, Hillf Danton wrote:
> [out of topic] Cc list is edited to quite mail agent warning:
> -"Dr. David Alan Gilbert"@v2.random; " <dgilbert@xxxxxxxxxx>
> +"Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
> -Pavel Emelyanov <xemul@xxxxxxxxxxxxx>"@v2.random
> +Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> -Michael Rapoport <RAPOPORT@xxxxxxxxxx>
> +Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
>
>
> On Thursday, November 03, 2016 3:34 AM Andrea Arcangeli wrote:
>> +
>> +#ifdef CONFIG_HUGETLB_PAGE
>> +/*
>> + * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
>> + * called with mmap_sem held, it will release mmap_sem before returning.
>> + */
>> +static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
>> + struct vm_area_struct *dst_vma,
>> + unsigned long dst_start,
>> + unsigned long src_start,
>> + unsigned long len,
>> + bool zeropage)
>> +{
>> + ssize_t err;
>> + pte_t *dst_pte;
>> + unsigned long src_addr, dst_addr;
>> + long copied;
>> + struct page *page;
>> + struct hstate *h;
>> + unsigned long vma_hpagesize;
>> + pgoff_t idx;
>> + u32 hash;
>> + struct address_space *mapping;
>> +
>> + /*
>> + * There is no default zero huge page for all huge page sizes as
>> + * supported by hugetlb. A PMD_SIZE huge pages may exist as used
>> + * by THP. Since we can not reliably insert a zero page, this
>> + * feature is not supported.
>> + */
>> + if (zeropage)
>> + return -EINVAL;
>
> Release mmap_sem before return?
>
>> +
>> + src_addr = src_start;
>> + dst_addr = dst_start;
>> + copied = 0;
>> + page = NULL;
>> + vma_hpagesize = vma_kernel_pagesize(dst_vma);
>> +
>> +retry:
>> + /*
>> + * On routine entry dst_vma is set. If we had to drop mmap_sem and
>> + * retry, dst_vma will be set to NULL and we must lookup again.
>> + */
>> + err = -EINVAL;
>> + if (!dst_vma) {
>> + dst_vma = find_vma(dst_mm, dst_start);
>
> In case of retry, s/dst_start/dst_addr/?
> And check if we find a valid vma?
>
>> @@ -182,6 +355,13 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
>> goto out_unlock;
>>
>> /*
>> + * If this is a HUGETLB vma, pass off to appropriate routine
>> + */
>> + if (dst_vma->vm_flags & VM_HUGETLB)
>> + return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
>> + src_start, len, false);
>
> Use is_vm_hugetlb_page()?
>
>
Thanks Hillf, all valid points. I will create another version of
this patch.
--
Mike Kravetz
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