From patchwork Fri Feb 26 07:18:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alistair Popple X-Patchwork-Id: 12105941 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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 0534FC433E9 for ; Fri, 26 Feb 2021 07:19:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 703A264ED3 for ; Fri, 26 Feb 2021 07:19:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 703A264ED3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ECAF68D0003; Fri, 26 Feb 2021 02:19:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EA5CE8D0001; Fri, 26 Feb 2021 02:19:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D1EC38D0003; Fri, 26 Feb 2021 02:19:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0236.hostedemail.com [216.40.44.236]) by kanga.kvack.org (Postfix) with ESMTP id B081B8D0001 for ; Fri, 26 Feb 2021 02:19:04 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 78789180A6F5D for ; Fri, 26 Feb 2021 07:19:04 +0000 (UTC) X-FDA: 77859567408.28.BC469F0 Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65]) by imf27.hostedemail.com (Postfix) with ESMTP id 002A680192E3 for ; Fri, 26 Feb 2021 07:18:56 +0000 (UTC) Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Thu, 25 Feb 2021 23:19:02 -0800 Received: from localhost (172.20.145.6) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 26 Feb 2021 07:19:01 +0000 From: Alistair Popple To: , , , CC: , , , , , , , , , Alistair Popple Subject: [PATCH v3 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Date: Fri, 26 Feb 2021 18:18:27 +1100 Message-ID: <20210226071832.31547-4-apopple@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210226071832.31547-1-apopple@nvidia.com> References: <20210226071832.31547-1-apopple@nvidia.com> MIME-Version: 1.0 X-Originating-IP: [172.20.145.6] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1614323942; bh=Er37msp1oYW9KFumvZeN3jL53UDEutwOeLFH26SFTLc=; h=From:To:CC:Subject:Date:Message-ID:X-Mailer:In-Reply-To: References:MIME-Version:Content-Transfer-Encoding:Content-Type: X-Originating-IP:X-ClientProxiedBy; b=hKjZzO4ykfe69uf2fhPuJL9Y1nm4cXKyYKKhZRX6MGkI0QuuPVp2JmEcu/nKK26zv zEzrSJummNBZcvDyCDSWGWwXaG36wmn9gql4nfINeuxFrn1bQuCoFvwHi4OMkeSmuU +/+nIKorxiP8K9YD9y4uwPiSGEMxlJFwInFa3iQ2FClj81AgXmXOkt4Za/q6CrsNP8 2cqNYyge6QBAAnmBIVau7kQOXqQ51Ai/OJHa8xpFvweS5Frk9fUX7row4+dYpp+/0A H643VxvLvK8qDHL/ZDxDEdloi7fM59PtLcfp9Wunw5Zqc3Hm0zCjKGw5uz5L1PGRm2 +fbiMs23poupA== X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 002A680192E3 X-Stat-Signature: te8s3or1zixp84xp8h8swxrto3acpn9i Received-SPF: none (nvidia.com>: No applicable sender policy available) receiver=imf27; identity=mailfrom; envelope-from=""; helo=hqnvemgate26.nvidia.com; client-ip=216.228.121.65 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614323936-356418 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: The behaviour of try_to_unmap_one() is difficult to follow because it performs different operations based on a fairly large set of flags used in different combinations. TTU_MUNLOCK is one such flag. However it is exclusively used by try_to_munlock() which specifies no other flags. Therefore rather than overload try_to_unmap_one() with unrelated behaviour split this out into it's own function and remove the flag. Signed-off-by: Alistair Popple Reviewed-by: Christoph Hellwig --- Given the comments on not needing to hold mmap_lock it was not 100% clear to me if it is safe to check vma->vma_flags & VM_LOCKED and if re-checking under the ptl was significant. I left the extra check in case it was, but it seems one of the checks is redunant as either the first check is racey or the second check is unneccsary. --- include/linux/rmap.h | 1 - mm/rmap.c | 47 ++++++++++++++++++++++++++++++++++++-------- 2 files changed, 39 insertions(+), 9 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 70085ca1a3fc..7f1ee411bd7b 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -87,7 +87,6 @@ struct anon_vma_chain { enum ttu_flags { TTU_MIGRATION = 0x1, /* migration mode */ - TTU_MUNLOCK = 0x2, /* munlock mode */ TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */ TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */ diff --git a/mm/rmap.c b/mm/rmap.c index ef9ef2694c58..850eecdd866a 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1391,10 +1391,6 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, struct mmu_notifier_range range; enum ttu_flags flags = (enum ttu_flags)(long)arg; - /* munlock has nothing to gain from examining un-locked vmas */ - if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED)) - return true; - if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) && is_zone_device_page(page) && !is_device_private_page(page)) return true; @@ -1455,8 +1451,6 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, page_vma_mapped_walk_done(&pvmw); break; } - if (flags & TTU_MUNLOCK) - continue; } /* Unexpected PMD-mapped THP? */ @@ -1775,6 +1769,44 @@ static int page_not_mapped(struct page *page) return !page_mapped(page); }; +static bool try_to_munlock_one(struct page *page, struct vm_area_struct *vma, + unsigned long address, void *arg) +{ + struct page_vma_mapped_walk pvmw = { + .page = page, + .vma = vma, + .address = address, + }; + bool ret = true; + + /* munlock has nothing to gain from examining un-locked vmas */ + if (!(vma->vm_flags & VM_LOCKED)) + return true; + + while (page_vma_mapped_walk(&pvmw)) { + /* + * If the page is mlock()d, we cannot swap it out. + * If it's recently referenced (perhaps page_referenced + * skipped over this mm) then we should reactivate it. + */ + if (vma->vm_flags & VM_LOCKED) { + /* PTE-mapped THP are never mlocked */ + if (!PageTransCompound(page)) { + /* + * Holding pte lock, we do *not* need + * mmap_lock here + */ + mlock_vma_page(page); + } + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + } + + return ret; +} + /** * try_to_munlock - try to munlock a page * @page: the page to be munlocked @@ -1787,8 +1819,7 @@ static int page_not_mapped(struct page *page) void try_to_munlock(struct page *page) { struct rmap_walk_control rwc = { - .rmap_one = try_to_unmap_one, - .arg = (void *)TTU_MUNLOCK, + .rmap_one = try_to_munlock_one, .done = page_not_mapped, .anon_lock = page_lock_anon_vma_read,