From patchwork Tue Feb 6 16:50:10 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Dufour X-Patchwork-Id: 869960 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zbWqB1F7Rz9s82 for ; Wed, 7 Feb 2018 04:36:54 +1100 (AEDT) Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3zbWq970Z9zF0xT for ; Wed, 7 Feb 2018 04:36:53 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=ldufour@linux.vnet.ibm.com; receiver=) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zbVpV6SyVzF10v for ; Wed, 7 Feb 2018 03:51:14 +1100 (AEDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w16GogT5087728 for ; Tue, 6 Feb 2018 11:51:12 -0500 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0b-001b2d01.pphosted.com with ESMTP id 2fyfvm13sa-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 06 Feb 2018 11:51:10 -0500 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 6 Feb 2018 16:51:08 -0000 Received: from b06cxnps3074.portsmouth.uk.ibm.com (9.149.109.194) by e06smtp13.uk.ibm.com (192.168.101.143) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Tue, 6 Feb 2018 16:51:01 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w16Gp1mp459188; Tue, 6 Feb 2018 16:51:01 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CA91011C054; Tue, 6 Feb 2018 16:44:24 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CC1B811C058; Tue, 6 Feb 2018 16:44:23 +0000 (GMT) Received: from nimbus.lab.toulouse-stg.fr.ibm.com (unknown [9.101.4.33]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 6 Feb 2018 16:44:23 +0000 (GMT) From: Laurent Dufour 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, Daniel Jordan Subject: [PATCH v7 24/24] powerpc/mm: Add speculative page fault Date: Tue, 6 Feb 2018 17:50:10 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1517935810-31177-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1517935810-31177-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18020616-0012-0000-0000-000005ABFC1A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18020616-0013-0000-0000-00001927B0CB Message-Id: <1517935810-31177-25-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2018-02-06_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802060212 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, npiggin@gmail.com, linux-mm@kvack.org, Tim Chen , haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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_SPECULATIVE_PAGE_FAULT 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 866446cf2d9a..104f3cc86b51 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -392,6 +392,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, unsigned long error_code) { struct vm_area_struct * vma; +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT + 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; @@ -459,6 +462,20 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, if (is_exec) flags |= FAULT_FLAG_INSTRUCTION; +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT + 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_SPECULATIVE_PAGE_FAULT */ + /* 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 @@ -489,7 +506,16 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, might_sleep(); } - vma = find_vma(mm, address); +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT + 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)) @@ -568,6 +594,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, up_read(¤t->mm->mmap_sem); +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT +done: +#endif if (unlikely(fault & VM_FAULT_ERROR)) return mm_fault_error(regs, address, fault);