Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751428AbbEXQCd (ORCPT ); Sun, 24 May 2015 12:02:33 -0400 Received: from mail-pa0-f41.google.com ([209.85.220.41]:33754 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751266AbbEXQC3 (ORCPT ); Sun, 24 May 2015 12:02:29 -0400 From: Jungseok Lee To: linux-arm-kernel@lists.infradead.org Cc: barami97@gmail.com, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 2/2] arm64: Implement vmalloc based thread_info allocator Date: Mon, 25 May 2015 01:02:20 +0900 Message-Id: <1432483340-23157-1-git-send-email-jungseoklee85@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3359 Lines: 92 Fork-routine sometimes fails to get a physically contiguous region for thread_info on 4KB page system although free memory is enough. That is, a physically contiguous region, which is currently 16KB, is not available since system memory is fragmented. This patch tries to solve the problem as allocating thread_info memory from vmalloc space, not 1:1 mapping one. The downside is one additional page allocation in case of vmalloc. However, vmalloc space is large enough, around 240GB, under a combination of 39-bit VA and 4KB page. Thus, it is not a big tradeoff for fork-routine service. Suggested-by: Sungjinn Chung Signed-off-by: Jungseok Lee Cc: Catalin Marinas Cc: Will Deacon Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org --- arch/arm64/Kconfig | 12 ++++++++++++ arch/arm64/include/asm/thread_info.h | 9 +++++++++ arch/arm64/kernel/process.c | 7 +++++++ 3 files changed, 28 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 99930cf..93c236a 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -536,6 +536,18 @@ config ARCH_SELECT_MEMORY_MODEL config HAVE_ARCH_PFN_VALID def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM +config ARCH_THREAD_INFO_ALLOCATOR + bool "Enable vmalloc based thread_info allocator (EXPERIMENTAL)" + depends on ARM64_4K_PAGES + default n + help + This feature enables vmalloc based thread_info allocator. It + prevents fork-routine from begin failed to obtain physically + contiguour region due to memory fragmentation on low system + memory platforms. + + If unsure, say N + config HW_PERF_EVENTS bool "Enable hardware performance counter support for perf events" depends on PERF_EVENTS diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index dcd06d1..e753e59 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -61,6 +61,15 @@ struct thread_info { #define init_thread_info (init_thread_union.thread_info) #define init_stack (init_thread_union.stack) +#ifdef CONFIG_ARCH_THREAD_INFO_ALLOCATOR +#define alloc_thread_info_node(tsk, node) \ +({ \ + __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE, VMALLOC_START, \ + VMALLOC_END, GFP_KERNEL, PAGE_KERNEL, 0, \ + NUMA_NO_NODE, __builtin_return_address(0)); \ +}) +#define free_thread_info(ti) vfree(ti) +#endif /* * how to get the current stack pointer from C */ diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index c506bee..c4b6aae 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -238,6 +238,13 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } +#ifdef CONFIG_ARCH_THREAD_INFO_ALLOCATOR +struct page *arch_thread_info_to_page(struct thread_info *ti) +{ + return vmalloc_to_page(ti); +} +#endif + asmlinkage void ret_from_fork(void) asm("ret_from_fork"); int copy_thread(unsigned long clone_flags, unsigned long stack_start, -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/