| Message ID | 20190218231319.178224-2-yuzhao@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/3] arm64: mm: use appropriate ctors for page tables | expand |
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@google.com> Assuming that was all, this patch makes sense to me. FWIW: Acked-by: Mark Rutland <mark.rutland@arm.com> 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 >
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@google.com> > > Assuming that was all, this patch makes sense to me. FWIW: > > Acked-by: Mark Rutland <mark.rutland@arm.com> 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 > >
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);
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. 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@google.com> --- arch/arm64/mm/mmu.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)