Messages in this thread | | | Date | Tue, 26 Feb 2019 15:12:31 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH v2 1/3] arm64: mm: use appropriate ctors for page tables |
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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@google.com> > --- > 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@arm.com>
Thanks, Mark.
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