From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754805AbdBNQpi (ORCPT ); Tue, 14 Feb 2017 11:45:38 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:36973 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754792AbdBNQp2 (ORCPT ); Tue, 14 Feb 2017 11:45:28 -0500 From: Laurent Dufour To: mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, npiggin@gmail.com Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] powerpc/mm: handle VM_FAULT_RETRY earlier Date: Tue, 14 Feb 2017 17:45:11 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17021416-0028-0000-0000-000002AA3C19 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17021416-0029-0000-0000-0000225F9C78 Message-Id: <42011273e3edc4176dc8045b3956dfd218259143.1487090656.git.ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-02-14_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702140162 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In do_page_fault() if handle_mm_fault() returns VM_FAULT_RETRY, retry the page fault handling before anything else. This would simplify the handling of the mmap_sem lock in this part of the code. Signed-off-by: Laurent Dufour --- arch/powerpc/mm/fault.c | 67 ++++++++++++++++++++++++++++--------------------- 1 file changed, 38 insertions(+), 29 deletions(-) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index ee09604bbe12..2a6bc7e6e69a 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -434,6 +434,26 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, * the fault. */ fault = handle_mm_fault(vma, address, flags); + + /* + * Handle the retry right now, the mmap_sem has been released in that + * case. + */ + if (unlikely(fault & VM_FAULT_RETRY)) { + /* We retry only once */ + if (flags & FAULT_FLAG_ALLOW_RETRY) { + /* + * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk + * of starvation. + */ + flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; + if (!fatal_signal_pending(current)) + goto retry; + } + /* We will enter mm_fault_error() below */ + } + if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) { if (fault & VM_FAULT_SIGSEGV) goto bad_area; @@ -445,38 +465,27 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, } /* - * Major/minor page fault accounting is only done on the - * initial attempt. If we go through a retry, it is extremely - * likely that the page will be found in page cache at that point. + * Major/minor page fault accounting. */ - if (flags & FAULT_FLAG_ALLOW_RETRY) { - if (fault & VM_FAULT_MAJOR) { - current->maj_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, - regs, address); + if (fault & VM_FAULT_MAJOR) { + current->maj_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, + regs, address); #ifdef CONFIG_PPC_SMLPAR - if (firmware_has_feature(FW_FEATURE_CMO)) { - u32 page_ins; - - preempt_disable(); - page_ins = be32_to_cpu(get_lppaca()->page_ins); - page_ins += 1 << PAGE_FACTOR; - get_lppaca()->page_ins = cpu_to_be32(page_ins); - preempt_enable(); - } -#endif /* CONFIG_PPC_SMLPAR */ - } else { - current->min_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, - regs, address); - } - if (fault & VM_FAULT_RETRY) { - /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk - * of starvation. */ - flags &= ~FAULT_FLAG_ALLOW_RETRY; - flags |= FAULT_FLAG_TRIED; - goto retry; + if (firmware_has_feature(FW_FEATURE_CMO)) { + u32 page_ins; + + preempt_disable(); + page_ins = be32_to_cpu(get_lppaca()->page_ins); + page_ins += 1 << PAGE_FACTOR; + get_lppaca()->page_ins = cpu_to_be32(page_ins); + preempt_enable(); } +#endif /* CONFIG_PPC_SMLPAR */ + } else { + current->min_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, + regs, address); } up_read(&mm->mmap_sem); -- 2.7.4