From patchwork Thu Aug 15 16:45:22 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 11096083 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 47A5A6C5 for ; Thu, 15 Aug 2019 16:48:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 36FC71FFBD for ; Thu, 15 Aug 2019 16:48:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2B75D28468; Thu, 15 Aug 2019 16:48:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B8CE01FFBD for ; Thu, 15 Aug 2019 16:48:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F3EFC6B02C8; Thu, 15 Aug 2019 12:48:40 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id EC9FE6B02CA; Thu, 15 Aug 2019 12:48:40 -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 DB7FD6B02CB; Thu, 15 Aug 2019 12:48:40 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id B48DE6B02C8 for ; Thu, 15 Aug 2019 12:48:40 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 5208D181AC9AE for ; Thu, 15 Aug 2019 16:48:40 +0000 (UTC) X-FDA: 75825246000.07.sofa17_68bc54e3b2c03 X-HE-Tag: sofa17_68bc54e3b2c03 X-Filterd-Recvd-Size: 5194 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Thu, 15 Aug 2019 16:48:39 +0000 (UTC) Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x7FGiToH030523 for ; Thu, 15 Aug 2019 09:48:38 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=WcQh8Odn+KCMMP8Sahh9ZuYRT9fwonfv6kfUW8pbYds=; b=GmXPhNzCnHLkVRKNUrhqgcufk6y/eRYuU1j4ecnOY4lSl/7ZSsInAgFTnW/9P2xB/oc2 z038drHvtu8UIV+zn/bxG4SBKr0fGb6cIth7YSlqOUT0Mnx/FPkrF2M1EfqsFLgQxKRg sWBGfW1uxGRHXlVLipCyX8IfkB2oUifR+sY= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2uda8sr9bx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Thu, 15 Aug 2019 09:48:38 -0700 Received: from mx-out.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Thu, 15 Aug 2019 09:48:37 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 5315C62E1C62; Thu, 15 Aug 2019 09:45:42 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig006.ftw2.facebook.com To: , , CC: , , , , , , , Song Liu Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v13 3/6] mm, thp: introduce FOLL_SPLIT_PMD Date: Thu, 15 Aug 2019 09:45:22 -0700 Message-ID: <20190815164525.1848545-4-songliubraving@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190815164525.1848545-1-songliubraving@fb.com> References: <20190815164525.1848545-1-songliubraving@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-15_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908150164 X-FB-Internal: deliver 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: X-Virus-Scanned: ClamAV using ClamSMTP This patches introduces a new foll_flag: FOLL_SPLIT_PMD. As the name says FOLL_SPLIT_PMD splits huge pmd for given mm_struct, the underlining huge page stays as-is. FOLL_SPLIT_PMD is useful for cases where we need to use regular pages, but would switch back to huge page and huge pmd on. One of such example is uprobe. The following patches use FOLL_SPLIT_PMD in uprobe. Reviewed-by: Oleg Nesterov Acked-by: Kirill A. Shutemov Signed-off-by: Song Liu --- include/linux/mm.h | 1 + mm/gup.c | 8 ++++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f189176dabed..74db879711eb 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2614,6 +2614,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, #define FOLL_COW 0x4000 /* internal GUP flag */ #define FOLL_ANON 0x8000 /* don't do file mappings */ #define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite: see below */ +#define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */ /* * NOTE on FOLL_LONGTERM: diff --git a/mm/gup.c b/mm/gup.c index 98f13ab37bac..c20afe800b3f 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -399,7 +399,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, spin_unlock(ptl); return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); } - if (flags & FOLL_SPLIT) { + if (flags & (FOLL_SPLIT | FOLL_SPLIT_PMD)) { int ret; page = pmd_page(*pmd); if (is_huge_zero_page(page)) { @@ -408,7 +408,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, split_huge_pmd(vma, pmd, address); if (pmd_trans_unstable(pmd)) ret = -EBUSY; - } else { + } else if (flags & FOLL_SPLIT) { if (unlikely(!try_get_page(page))) { spin_unlock(ptl); return ERR_PTR(-ENOMEM); @@ -420,6 +420,10 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, put_page(page); if (pmd_none(*pmd)) return no_page_table(vma, flags); + } else { /* flags & FOLL_SPLIT_PMD */ + spin_unlock(ptl); + split_huge_pmd(vma, pmd, address); + ret = pte_alloc(mm, pmd) ? -ENOMEM : 0; } return ret ? ERR_PTR(ret) :