Hi,
On Mon, Feb 18, 2019 at 04:13:18PM -0700, Yu Zhao wrote:
> init_mm doesn't require page table lock to be initialized at
> any level. Add a separate page table allocator for it, and the
> new one skips page table ctors.
Just to check, in a previous reply you mentioned we need to call the
ctors for our efi_mm, since we use apply_to_page_range() on that. Is
that only because apply_to_pte_range() tries to take the ptl for non
init_mm?
... or did I miss something else?
> The ctors allocate memory when ALLOC_SPLIT_PTLOCKS is set. Not
> calling them avoids memory leak in case we call pte_free_kernel()
> on init_mm.
>
> Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Assuming that was all, this patch makes sense to me. FWIW:
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Thanks,
Mark.
> ---
> arch/arm64/mm/mmu.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index fa7351877af3..e8bf8a6300e8 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -370,6 +370,16 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
> } while (pgdp++, addr = next, addr != end);
> }
>
> +static phys_addr_t pgd_kernel_pgtable_alloc(int shift)
> +{
> + void *ptr = (void *)__get_free_page(PGALLOC_GFP);
> + BUG_ON(!ptr);
> +
> + /* Ensure the zeroed page is visible to the page table walker */
> + dsb(ishst);
> + return __pa(ptr);
> +}
> +
> static phys_addr_t pgd_pgtable_alloc(int shift)
> {
> void *ptr = (void *)__get_free_page(PGALLOC_GFP);
> @@ -591,7 +601,7 @@ static int __init map_entry_trampoline(void)
> /* Map only the text into the trampoline page table */
> memset(tramp_pg_dir, 0, PGD_SIZE);
> __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE,
> - prot, pgd_pgtable_alloc, 0);
> + prot, pgd_kernel_pgtable_alloc, 0);
>
> /* Map both the text and data into the kernel page table */
> __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
> @@ -1067,7 +1077,8 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
> flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
>
> __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
> - size, PAGE_KERNEL, pgd_pgtable_alloc, flags);
> + size, PAGE_KERNEL, pgd_kernel_pgtable_alloc,
> + flags);
>
> return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
> altmap, want_memblock);
> --
> 2.21.0.rc0.258.g878e2cd30e-goog
>
