From: Will Deacon <will.deacon@arm.com>
To: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nick Piggin <npiggin@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Joel Fernandes <joel@joelfernandes.org>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-mm@kvack.org, mark.rutland@arm.com
Subject: Re: [PATCH] arm64: mm: enable per pmd page table lock
Date: Mon, 18 Feb 2019 15:12:23 +0000 [thread overview]
Message-ID: <20190218151223.GB16091@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <20190214211642.2200-1-yuzhao@google.com>
[+Mark]
On Thu, Feb 14, 2019 at 02:16:42PM -0700, Yu Zhao wrote:
> Switch from per mm_struct to per pmd page table lock by enabling
> ARCH_ENABLE_SPLIT_PMD_PTLOCK. This provides better granularity for
> large system.
>
> I'm not sure if there is contention on mm->page_table_lock. Given
> the option comes at no cost (apart from initializing more spin
> locks), why not enable it now.
>
> Signed-off-by: Yu Zhao <yuzhao@google.com>
> ---
> arch/arm64/Kconfig | 3 +++
> arch/arm64/include/asm/pgalloc.h | 12 +++++++++++-
> arch/arm64/include/asm/tlb.h | 5 ++++-
> 3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index a4168d366127..104325a1ffc3 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -872,6 +872,9 @@ config ARCH_WANT_HUGE_PMD_SHARE
> config ARCH_HAS_CACHE_LINE_SIZE
> def_bool y
>
> +config ARCH_ENABLE_SPLIT_PMD_PTLOCK
> + def_bool y
> +
> config SECCOMP
> bool "Enable seccomp to safely compute untrusted bytecode"
> ---help---
> diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
> index 52fa47c73bf0..dabba4b2c61f 100644
> --- a/arch/arm64/include/asm/pgalloc.h
> +++ b/arch/arm64/include/asm/pgalloc.h
> @@ -33,12 +33,22 @@
>
> static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
> {
> - return (pmd_t *)__get_free_page(PGALLOC_GFP);
> + struct page *page;
> +
> + page = alloc_page(PGALLOC_GFP);
> + if (!page)
> + return NULL;
> + if (!pgtable_pmd_page_ctor(page)) {
> + __free_page(page);
> + return NULL;
> + }
> + return page_address(page);
I'm a bit worried as to how this interacts with the page-table code in
arch/arm64/mm/mmu.c when pgd_pgtable_alloc is used as the allocator. It
looks like that currently always calls pgtable_page_ctor(), regardless of
level. Do we now need a separate allocator function for the PMD level?
Will
next prev parent reply other threads:[~2019-02-18 15:12 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 21:16 [PATCH] arm64: mm: enable per pmd page table lock Yu Zhao
2019-02-18 15:12 ` Will Deacon [this message]
2019-02-18 19:49 ` Yu Zhao
2019-02-18 20:48 ` Yu Zhao
2019-02-19 4:09 ` Anshuman Khandual
2019-02-18 23:13 ` [PATCH v2 1/3] arm64: mm: use appropriate ctors for page tables Yu Zhao
2019-02-18 23:13 ` [PATCH v2 2/3] arm64: mm: don't call page table ctors for init_mm Yu Zhao
2019-02-26 15:13 ` Mark Rutland
2019-03-09 3:52 ` Yu Zhao
2019-02-18 23:13 ` [PATCH v2 3/3] arm64: mm: enable per pmd page table lock Yu Zhao
2019-02-19 4:21 ` [PATCH v2 1/3] arm64: mm: use appropriate ctors for page tables Anshuman Khandual
2019-02-19 5:32 ` Yu Zhao
2019-02-19 6:17 ` Anshuman Khandual
2019-02-19 22:28 ` Yu Zhao
2019-02-20 10:27 ` Anshuman Khandual
2019-02-20 12:24 ` Matthew Wilcox
2019-02-20 20:22 ` Yu Zhao
2019-02-20 20:59 ` Matthew Wilcox
2019-02-20 1:34 ` Matthew Wilcox
2019-02-20 3:20 ` Anshuman Khandual
2019-02-20 21:03 ` Matthew Wilcox
2019-02-26 15:12 ` Mark Rutland
2019-03-09 4:01 ` Yu Zhao
2019-03-10 1:19 ` [PATCH v3 " Yu Zhao
2019-03-10 1:19 ` [PATCH v3 2/3] arm64: mm: don't call page table ctors for init_mm Yu Zhao
2019-03-10 1:19 ` [PATCH v3 3/3] arm64: mm: enable per pmd page table lock Yu Zhao
2019-03-11 8:28 ` Anshuman Khandual
2019-03-11 23:10 ` Yu Zhao
2019-03-11 12:12 ` Mark Rutland
2019-03-11 12:57 ` Anshuman Khandual
2019-03-11 23:11 ` Yu Zhao
2019-03-11 7:45 ` [PATCH v3 1/3] arm64: mm: use appropriate ctors for page tables Anshuman Khandual
2019-03-11 23:23 ` Yu Zhao
2019-03-12 0:57 ` [PATCH v4 1/4] " Yu Zhao
2019-03-12 0:57 ` [PATCH v4 2/4] arm64: mm: don't call page table ctors for init_mm Yu Zhao
2019-03-12 0:57 ` [PATCH v4 3/4] arm64: mm: call ctor for stage2 pmd page Yu Zhao
2019-03-12 0:57 ` [PATCH v4 4/4] arm64: mm: enable per pmd page table lock Yu Zhao
2019-02-19 3:08 ` [PATCH] " Anshuman Khandual
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