On Tue, Feb 26, 2019 at 03:13:07PM +0000, Mark Rutland wrote:
> 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?
Precisely.
> ... 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.
> 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
> >
