Hi,
On Mon, Feb 18, 2019 at 04:13:17PM -0700, Yu Zhao wrote:
> For pte page, use pgtable_page_ctor(); for pmd page, use
> pgtable_pmd_page_ctor() if not folded; and for the rest (pud,
> p4d and pgd), don't use any.
>
> Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
> ---
> arch/arm64/mm/mmu.c | 33 +++++++++++++++++++++------------
> 1 file changed, 21 insertions(+), 12 deletions(-)
[...]
> -static phys_addr_t pgd_pgtable_alloc(void)
> +static phys_addr_t pgd_pgtable_alloc(int shift)
> {
> void *ptr = (void *)__get_free_page(PGALLOC_GFP);
> - if (!ptr || !pgtable_page_ctor(virt_to_page(ptr)))
> - BUG();
> + BUG_ON(!ptr);
> +
> + /*
> + * Initialize page table locks in case later we need to
> + * call core mm functions like apply_to_page_range() on
> + * this pre-allocated page table.
> + */
> + if (shift == PAGE_SHIFT)
> + BUG_ON(!pgtable_page_ctor(virt_to_page(ptr)));
> + else if (shift == PMD_SHIFT && PMD_SHIFT != PUD_SHIFT)
> + BUG_ON(!pgtable_pmd_page_ctor(virt_to_page(ptr)));
IIUC, this is for nopmd kernels, where we only have real PGD and PTE
levels of table. From my PoV, that would be clearer if we did:
else if (shift == PMD_SHIFT && !is_defined(__PAGETABLE_PMD_FOLDED))
... though IMO it would be a bit nicer if the generic
pgtable_pmd_page_ctor() were nop'd out for __PAGETABLE_PMD_FOLDED
builds, so that callers don't have to be aware of folding.
I couldn't think of a nicer way of distinguishing levels of table, and
having separate function pointers for each level seems over-the-top, so
otehr than that this looks good to me.
Assuming you're happy with the above change:
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Thanks,
Mark.
