>
> When creating a hugetlb mapping, attempt PUD_SIZE alignment if the
> following conditions are met:
> - Address passed to mmap or shmat is NULL
> - The mapping is flaged as shared
> - The mapping is at least PUD_SIZE in length
> If a PUD_SIZE aligned mapping can not be created, then fall back to a
> huge page size mapping.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> ---
> fs/hugetlbfs/inode.c | 29 +++++++++++++++++++++++++++--
> 1 file changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 540ddc9..22b2e38 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -175,6 +175,17 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
> struct vm_area_struct *vma;
> struct hstate *h = hstate_file(file);
> struct vm_unmapped_area_info info;
> + bool pud_size_align = false;
> + unsigned long ret_addr;
> +
> + /*
> + * If PMD sharing is enabled, align to PUD_SIZE to facilitate
> + * sharing. Only attempt alignment if no address was passed in,
> + * flags indicate sharing and size is big enough.
> + */
> + if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) &&
> + !addr && flags & MAP_SHARED && len >= PUD_SIZE)
> + pud_size_align = true;
>
> if (len & ~huge_page_mask(h))
> return -EINVAL;
> @@ -199,9 +210,23 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
> info.length = len;
> info.low_limit = TASK_UNMAPPED_BASE;
> info.high_limit = TASK_SIZE;
> - info.align_mask = PAGE_MASK & ~huge_page_mask(h);
> + if (pud_size_align)
> + info.align_mask = PAGE_MASK & (PUD_SIZE - 1);
> + else
> + info.align_mask = PAGE_MASK & ~huge_page_mask(h);
> info.align_offset = 0;
> - return vm_unmapped_area(&info);
> + ret_addr = vm_unmapped_area(&info);
> +
> + /*
> + * If failed with PUD_SIZE alignment, try again with huge page
> + * size alignment.
> + */
Can we avoid going another round as long as it is a file with
the PUD page size?
Hillf
> + if ((ret_addr & ~PAGE_MASK) && pud_size_align) {
> + info.align_mask = PAGE_MASK & ~huge_page_mask(h);
> + ret_addr = vm_unmapped_area(&info);
> + }
> +
> + return ret_addr;
> }
> #endif
>
> --
> 2.4.3
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