From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D716C2D0EA for ; Wed, 8 Apr 2020 08:52:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D04320771 for ; Wed, 8 Apr 2020 08:52:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727705AbgDHIwK (ORCPT ); Wed, 8 Apr 2020 04:52:10 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:55916 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726795AbgDHIwJ (ORCPT ); Wed, 8 Apr 2020 04:52:09 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0388YkB6107935 for ; Wed, 8 Apr 2020 04:52:08 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 30920w5a8a-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 08 Apr 2020 04:52:07 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 8 Apr 2020 09:51:49 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0388q1b517957062 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 8 Apr 2020 08:52:01 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 134F152052; Wed, 8 Apr 2020 08:52:01 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.153.96]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 29EFE52057; Wed, 8 Apr 2020 08:52:00 +0000 (GMT) Subject: Re: [RFC][Qusetion] the value of cleared_(ptes|pmds|puds|p4ds) in struct mmu_gather To: Peter Zijlstra , Zhenyu Ye Cc: npiggin@gmail.com, will.deacon@arm.com, mingo@kernel.org, torvalds@linux-foundation.org, Vasily Gorbik , akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, Marc Zyngier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, arm@kernel.org, xiexiangyou@huawei.com, Gerald Schaefer , linux-s390 References: <20200330121654.GL20696@hirez.programming.kicks-ass.net> From: Christian Borntraeger Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200330121654.GL20696@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 20040808-0012-0000-0000-000003A08D20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20040808-0013-0000-0000-000021DDB182 Message-Id: <68affa6e-44cd-37e3-cdfc-8eec31c4097e@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-07_10:2020-04-07,2020-04-07 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 adultscore=0 impostorscore=0 spamscore=0 priorityscore=1501 bulkscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=890 mlxscore=0 clxscore=1015 suspectscore=2 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004080065 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, just saw that now.. On 30.03.20 14:16, Peter Zijlstra wrote: > On Sat, Mar 28, 2020 at 12:30:50PM +0800, Zhenyu Ye wrote: >> Hi all, >> >> commit a6d60245 "Track which levels of the page tables have been cleared" >> added cleared_(ptes|pmds|puds|p4ds) in struct mmu_gather, and the values >> of them are set in some places. For example: >> >> In include/asm-generic/tlb.h, pte_free_tlb() set the tlb->cleared_pmds: >> ---8<--- >> #ifndef pte_free_tlb >> #define pte_free_tlb(tlb, ptep, address) \ >> do { \ >> __tlb_adjust_range(tlb, address, PAGE_SIZE); \ >> tlb->freed_tables = 1; \ >> tlb->cleared_pmds = 1; \ >> __pte_free_tlb(tlb, ptep, address); \ >> } while (0) >> #endif >> ---8<--- >> >> >> However, in arch/s390/include/asm/tlb.h, pte_free_tlb() set the tlb->cleared_ptes: >> ---8<--- >> static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, >> unsigned long address) >> { >> __tlb_adjust_range(tlb, address, PAGE_SIZE); >> tlb->mm->context.flush_mm = 1; >> tlb->freed_tables = 1; >> tlb->cleared_ptes = 1; >> /* >> * page_table_free_rcu takes care of the allocation bit masks >> * of the 2K table fragments in the 4K page table page, >> * then calls tlb_remove_table. >> */ >> page_table_free_rcu(tlb, (unsigned long *) pte, address); >> } >> ---8<--- adding Gerald and Vasily. Gerald can you have a look? >> >> >> In my view, the cleared_(ptes|pmds|puds) and (pte|pmd|pud)_free_tlb >> correspond one-to-one. So we should set cleared_ptes in pte_free_tlb(), >> then use it when needed. > > So pte_free_tlb() clears a table of PTE entries, or a PMD level entity, > also see free_pte_range(). So the generic code makes sense to me. The > PTE level invalidations will have happened on tlb_remove_tlb_entry(). > >> I'm very confused about this. Which is wrong? Or is there something >> I understand wrong? > > I agree the s390 case is puzzling, Martin does s390 need a PTE level > invalidate for removing a PTE table or was this a mistake? >