From patchwork Thu Mar 19 03:56:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Aneesh Kumar K.V" X-Patchwork-Id: 11446447 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 78FB21668 for ; Thu, 19 Mar 2020 03:57:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 434C920722 for ; Thu, 19 Mar 2020 03:57:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 434C920722 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 534776B0007; Wed, 18 Mar 2020 23:57:46 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 4E42C6B0008; Wed, 18 Mar 2020 23:57:46 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3FABC6B0078; Wed, 18 Mar 2020 23:57:46 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0076.hostedemail.com [216.40.44.76]) by kanga.kvack.org (Postfix) with ESMTP id 259276B0007 for ; Wed, 18 Mar 2020 23:57:46 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id AFA77282B for ; Thu, 19 Mar 2020 03:57:45 +0000 (UTC) X-FDA: 76610752890.23.form91_269f14037fc05 X-Spam-Summary: 2,0,0,c15c81603dbf5b14,d41d8cd98f00b204,aneesh.kumar@linux.ibm.com,,RULES_HIT:41:69:355:379:541:800:960:968:973:988:989:1260:1261:1311:1314:1345:1359:1431:1437:1515:1535:1544:1605:1711:1730:1747:1777:1792:1981:2194:2199:2393:2559:2562:2903:2915:3138:3139:3140:3141:3142:3698:3865:3866:3867:3868:3870:3871:3872:3874:4119:4250:4321:4605:5007:6117:6119:6261:6630:7875:7903:8660:9040:10004:11026:11473:11657:11658:11914:12043:12048:12295:12296:12297:12438:12555:12663:12679:12895:13148:13230:13894:14181:14394:14721:21080:21324:21451:21627:21740:21939:21966:21990:30003:30012:30054:30069:30070,0,RBL:148.163.158.5:@linux.ibm.com:.lbl8.mailshell.net-64.100.201.201 62.2.0.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:16,LUA_SUMMARY:none X-HE-Tag: form91_269f14037fc05 X-Filterd-Recvd-Size: 8113 Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Thu, 19 Mar 2020 03:57:45 +0000 (UTC) Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 02J3Wcp2124329; Wed, 18 Mar 2020 23:57:40 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 2yu7acudpt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 18 Mar 2020 23:57:39 -0400 Received: from m0098416.ppops.net (m0098416.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 02J3XG37127518; Wed, 18 Mar 2020 23:57:39 -0400 Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0b-001b2d01.pphosted.com with ESMTP id 2yu7acudpn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 18 Mar 2020 23:57:39 -0400 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id 02J3ut5X029362; Thu, 19 Mar 2020 03:57:39 GMT Received: from b01cxnp22033.gho.pok.ibm.com (b01cxnp22033.gho.pok.ibm.com [9.57.198.23]) by ppma04dal.us.ibm.com with ESMTP id 2yrpw6y6b3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 19 Mar 2020 03:57:38 +0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 02J3vcRv54591818 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Mar 2020 03:57:38 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1F3A6112064; Thu, 19 Mar 2020 03:57:38 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9DB1D112062; Thu, 19 Mar 2020 03:57:34 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.199.34.213]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 19 Mar 2020 03:57:34 +0000 (GMT) From: "Aneesh Kumar K.V" To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org Cc: npiggin@gmail.com, paulus@ozlabs.org, leonardo@linux.ibm.com, kirill@shutemov.name, "Aneesh Kumar K.V" Subject: [PATCH v2 20/22] powerpc/mm/book3s64: Avoid sending IPI on clearing PMD Date: Thu, 19 Mar 2020 09:26:07 +0530 Message-Id: <20200319035609.158654-21-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200319035609.158654-1-aneesh.kumar@linux.ibm.com> References: <20200319035609.158654-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.645 definitions=2020-03-18_10:2020-03-18,2020-03-18 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 mlxscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 clxscore=1015 adultscore=0 spamscore=0 impostorscore=0 malwarescore=0 mlxlogscore=873 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003190013 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Now that all the lockless page table walk is careful w.r.t the PTE address returned, we can now revert commit: 13bd817bb884 ("powerpc/thp: Serialize pmd clear against a linux page table walk.") We also drop the equivalent IPI from other pte updates routines. We still keep IPI in hash pmdp collapse and that is to take care of parallel hash page table insert. The radix pmdp collapse flush can possibly be removed once I am sure generic code doesn't have the any expectations around parallel gup walk. This speeds up Qemu guest RAM del/unplug time as below 128 core, 496GB guest: Without patch: munmap start: timer = 13162 ms, PID=7684 munmap finish: timer = 95312 ms, PID=7684 - delta = 82150 ms With patch: munmap start: timer = 196449 ms, PID=6681 munmap finish: timer = 196488 ms, PID=6681 - delta = 39ms Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/mm/book3s64/hash_pgtable.c | 11 ----------- arch/powerpc/mm/book3s64/pgtable.c | 8 -------- arch/powerpc/mm/book3s64/radix_pgtable.c | 19 +++++++------------ 3 files changed, 7 insertions(+), 31 deletions(-) diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c index 64733b9cb20a..64ca375278dc 100644 --- a/arch/powerpc/mm/book3s64/hash_pgtable.c +++ b/arch/powerpc/mm/book3s64/hash_pgtable.c @@ -363,17 +363,6 @@ pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm, * hash fault look at them. */ memset(pgtable, 0, PTE_FRAG_SIZE); - /* - * Serialize against find_current_mm_pte variants which does lock-less - * lookup in page tables with local interrupts disabled. For huge pages - * it casts pmd_t to pte_t. Since format of pte_t is different from - * pmd_t we want to prevent transit from pmd pointing to page table - * to pmd pointing to huge page (and back) while interrupts are disabled. - * We clear pmd to possibly replace it with page table pointer in - * different code paths. So make sure we wait for the parallel - * find_curren_mm_pte to finish. - */ - serialize_against_pte_lookup(mm); return old_pmd; } diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c index 2bf7e1b4fd82..93fc3be41ed9 100644 --- a/arch/powerpc/mm/book3s64/pgtable.c +++ b/arch/powerpc/mm/book3s64/pgtable.c @@ -109,14 +109,6 @@ pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, old_pmd = pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, _PAGE_INVALID); flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); - /* - * This ensures that generic code that rely on IRQ disabling - * to prevent a parallel THP split work as expected. - * - * Marking the entry with _PAGE_INVALID && ~_PAGE_PRESENT requires - * a special case check in pmd_access_permitted. - */ - serialize_against_pte_lookup(vma->vm_mm); return __pmd(old_pmd); } diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c index dd1bea45325c..0a78b10c256c 100644 --- a/arch/powerpc/mm/book3s64/radix_pgtable.c +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -957,7 +957,13 @@ pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long addre pmd = *pmdp; pmd_clear(pmdp); - /*FIXME!! Verify whether we need this kick below */ + /* + * pmdp collapse_flush need to ensure that there are no parallel gup + * walk after this call. This is needed so that we can have stable + * page ref count when collapsing a page. We don't allow a collapse page + * if we have gup taken on the page. We can ensure that by sending IPI + * because gup walk happens with IRQ disabled. + */ serialize_against_pte_lookup(vma->vm_mm); radix__flush_tlb_collapsed_pmd(vma->vm_mm, address); @@ -1018,17 +1024,6 @@ pmd_t radix__pmdp_huge_get_and_clear(struct mm_struct *mm, old = radix__pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0); old_pmd = __pmd(old); - /* - * Serialize against find_current_mm_pte which does lock-less - * lookup in page tables with local interrupts disabled. For huge pages - * it casts pmd_t to pte_t. Since format of pte_t is different from - * pmd_t we want to prevent transit from pmd pointing to page table - * to pmd pointing to huge page (and back) while interrupts are disabled. - * We clear pmd to possibly replace it with page table pointer in - * different code paths. So make sure we wait for the parallel - * find_current_mm_pte to finish. - */ - serialize_against_pte_lookup(mm); return old_pmd; }