Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965178AbeALR1k (ORCPT + 1 other); Fri, 12 Jan 2018 12:27:40 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33736 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965123AbeALR1i (ORCPT ); Fri, 12 Jan 2018 12:27:38 -0500 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 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 Subject: [PATCH v6 23/24] x86/mm: Add speculative pagefault handling Date: Fri, 12 Jan 2018 18:26:07 +0100 X-Mailer: git-send-email 2.7.4 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> X-TM-AS-GCONF: 00 x-cbid: 18011217-0040-0000-0000-000004041B77 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011217-0041-0000-0000-000026077DF9 Message-Id: <1515777968-867-24-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-01-12_09:,, 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-1801120238 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Peter Zijlstra Try a speculative fault before acquiring mmap_sem, if it returns with VM_FAULT_RETRY continue with the mmap_sem acquisition and do the traditional fault. Signed-off-by: Peter Zijlstra (Intel) [Clearing of FAULT_FLAG_ALLOW_RETRY is now done in handle_speculative_fault()] [Retry with usual fault path in the case VM_ERROR is returned by handle_speculative_fault(). This allows signal to be delivered] [Don't build SPF call if !CONFIG_SPF] [Try speculative fault path only for multi threaded processes] [Try to the VMA fetch during the speculative path in case of retry] Signed-off-by: Laurent Dufour --- arch/x86/mm/fault.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 06fe3d51d385..8db69a116521 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1242,6 +1242,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address) { struct vm_area_struct *vma; +#ifdef CONFIG_SPF + struct vm_area_struct *spf_vma = NULL; +#endif struct task_struct *tsk; struct mm_struct *mm; int fault, major = 0; @@ -1339,6 +1342,27 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, if (error_code & X86_PF_INSTR) flags |= FAULT_FLAG_INSTRUCTION; +#ifdef CONFIG_SPF + if ((error_code & X86_PF_USER) && (atomic_read(&mm->mm_users) > 1)) { + fault = handle_speculative_fault(mm, address, flags, + &spf_vma); + + if (!(fault & VM_FAULT_RETRY)) { + if (!(fault & VM_FAULT_ERROR)) { + perf_sw_event(PERF_COUNT_SW_SPF, 1, + regs, address); + goto done; + } + /* + * In case of error we need the pkey value, but + * can't get it from the spf_vma as it is only returned + * when VM_FAULT_RETRY is returned. So we have to + * retry the page fault with the mmap_sem grabbed. + */ + } + } +#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 @@ -1372,7 +1396,16 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, 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)) { bad_area(regs, error_code, address); return; @@ -1458,6 +1491,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, return; } +#ifdef CONFIG_SPF +done: +#endif /* * Major/minor page fault accounting. If any of the events * returned VM_FAULT_MAJOR, we account it as a major fault. -- 2.7.4