From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id 78C2B6B027E for ; Fri, 12 Jan 2018 12:27:43 -0500 (EST) Received: by mail-qk0-f199.google.com with SMTP id z65so5391798qkb.22 for ; Fri, 12 Jan 2018 09:27:43 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id t7si2096718qkf.125.2018.01.12.09.27.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Jan 2018 09:27:42 -0800 (PST) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w0CHORxW020831 for ; Fri, 12 Jan 2018 12:27:41 -0500 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ff0bvknuu-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 12 Jan 2018 12:27:41 -0500 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 12 Jan 2018 17:27:38 -0000 From: Laurent Dufour Subject: [PATCH v6 24/24] powerpc/mm: Add speculative page fault Date: Fri, 12 Jan 2018 18:26:08 +0100 In-Reply-To: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> Message-Id: <1515777968-867-25-git-send-email-ldufour@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org This patch enable the speculative page fault on the PowerPC architecture. This will try a speculative page fault without holding the mmap_sem, if it returns with VM_FAULT_RETRY, the mmap_sem is acquired and the traditional page fault processing is done. The speculative path is only tried for multithreaded process as there is no risk of contention on the mmap_sem otherwise. Build on if CONFIG_SPF is defined (currently for BOOK3S_64 && SMP). Signed-off-by: Laurent Dufour --- arch/powerpc/mm/fault.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 6e1e39035380..67b4c6aa7975 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -384,6 +384,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, unsigned long error_code) { struct vm_area_struct * vma; +#ifdef CONFIG_SPF + struct vm_area_struct *spf_vma = NULL; +#endif struct mm_struct *mm = current->mm; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; int is_exec = TRAP(regs) == 0x400; @@ -447,6 +450,20 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, if (is_exec) flags |= FAULT_FLAG_INSTRUCTION; +#ifdef CONFIG_SPF + if (is_user && (atomic_read(&mm->mm_users) > 1)) { + /* let's try a speculative page fault without grabbing the + * mmap_sem. + */ + fault = handle_speculative_fault(mm, address, flags, &spf_vma); + if (!(fault & VM_FAULT_RETRY)) { + perf_sw_event(PERF_COUNT_SW_SPF, 1, + regs, address); + goto done; + } + } +#endif /* CONFIG_SPF */ + /* When running in the kernel we expect faults to occur only to * addresses in user space. All other faults represent errors in the * kernel and should generate an OOPS. Unfortunately, in the case of an @@ -477,7 +494,16 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, might_sleep(); } - vma = find_vma(mm, address); +#ifdef CONFIG_SPF + if (spf_vma) { + if (can_reuse_spf_vma(spf_vma, address)) + vma = spf_vma; + else + vma = find_vma(mm, address); + spf_vma = NULL; + } else +#endif + vma = find_vma(mm, address); if (unlikely(!vma)) return bad_area(regs, address); if (likely(vma->vm_start <= address)) @@ -531,6 +557,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, up_read(¤t->mm->mmap_sem); +#ifdef CONFIG_SPF +done: +#endif if (unlikely(fault & VM_FAULT_ERROR)) return mm_fault_error(regs, address, fault); -- 2.7.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org