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=-9.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 4893DC33CB2 for ; Fri, 31 Jan 2020 10:01:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DADA4206F0 for ; Fri, 31 Jan 2020 10:01:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=shipmail.org header.i=@shipmail.org header.b="GoYqswts" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728291AbgAaKBN (ORCPT ); Fri, 31 Jan 2020 05:01:13 -0500 Received: from pio-pvt-msa3.bahnhof.se ([79.136.2.42]:56100 "EHLO pio-pvt-msa3.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728160AbgAaKBM (ORCPT ); Fri, 31 Jan 2020 05:01:12 -0500 Received: from localhost (localhost [127.0.0.1]) by pio-pvt-msa3.bahnhof.se (Postfix) with ESMTP id C790F3FD13; Fri, 31 Jan 2020 11:01:09 +0100 (CET) Authentication-Results: pio-pvt-msa3.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=GoYqswts; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se Received: from pio-pvt-msa3.bahnhof.se ([127.0.0.1]) by localhost (pio-pvt-msa3.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SHs2n_T6gOEa; Fri, 31 Jan 2020 11:01:08 +0100 (CET) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by pio-pvt-msa3.bahnhof.se (Postfix) with ESMTPA id 243553FC05; Fri, 31 Jan 2020 11:01:07 +0100 (CET) Received: from localhost.localdomain.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 714F1360093; Fri, 31 Jan 2020 11:01:07 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1580464867; bh=fAsEaB9XUES6Qvb9+NO+aU7Kv7uOMIgjlqELbkBztfo=; h=From:To:Cc:Subject:Date:From; b=GoYqswts+r1eIgAFejbB8049UuZsWY2tUAMf9kM07OHNyvFVEGxt3Ctq+W35kN3rz uiEc4fxS9GEx4D3NH1HhU8Bl+LSwE+enaE0OB/2jFRn7Q67ppqn2HlUggXj5prsv8V YKI37tidhdfb5a+kRPd9Rg4fhD5zQXaWuqgWcHRE= From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m=20=28VMware=29?= To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Thomas Hellstrom , Steven Price Subject: [PATCH] mm/mapping_dirty_helpers: Update huge page-table entry callbacks Date: Fri, 31 Jan 2020 11:00:52 +0100 Message-Id: <20200131100052.58761-1-thomas_os@shipmail.org> X-Mailer: git-send-email 2.21.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Hellstrom Following the update of pagewalk code commit a07984d48146 ("mm: pagewalk: add p4d_entry() and pgd_entry()") we can modify the mapping_dirty_helpers' huge page-table entry callbacks to avoid splitting when a huge pud or -pmd is encountered. Signed-off-by: Thomas Hellstrom Cc: Steven Price --- mm/mapping_dirty_helpers.c | 42 ++++++++++++++++++++++++++++++++++---- 1 file changed, 38 insertions(+), 4 deletions(-) diff --git a/mm/mapping_dirty_helpers.c b/mm/mapping_dirty_helpers.c index 71070dda9643..2c7d03675903 100644 --- a/mm/mapping_dirty_helpers.c +++ b/mm/mapping_dirty_helpers.c @@ -111,26 +111,60 @@ static int clean_record_pte(pte_t *pte, unsigned long addr, return 0; } -/* wp_clean_pmd_entry - The pagewalk pmd callback. */ +/* + * wp_clean_pmd_entry - The pagewalk pmd callback. + * + * Dirty-tracking should take place on the PTE level, so + * WARN() if encountering a dirty huge pmd. + * Furthermore, never split huge pmds, since that currently + * causes dirty info loss. The pagefault handler should do + * that if needed. + */ static int wp_clean_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { - /* Dirty-tracking should be handled on the pte level */ pmd_t pmdval = pmd_read_atomic(pmd); + if (!pmd_trans_unstable(&pmdval)) + return 0; + + if (pmd_none(pmdval)) { + walk->action = ACTION_AGAIN; + return 0; + } + + /* Huge pmd, present or migrated */ + walk->action = ACTION_CONTINUE; if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval)) WARN_ON(pmd_write(pmdval) || pmd_dirty(pmdval)); return 0; } -/* wp_clean_pud_entry - The pagewalk pud callback. */ +/* + * wp_clean_pud_entry - The pagewalk pud callback. + * + * Dirty-tracking should take place on the PTE level, so + * WARN() if encountering a dirty huge puds. + * Furthermore, never split huge puds, since that currently + * causes dirty info loss. The pagefault handler should do + * that if needed. + */ static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end, struct mm_walk *walk) { - /* Dirty-tracking should be handled on the pte level */ pud_t pudval = READ_ONCE(*pud); + if (!pud_trans_unstable(&pudval)) + return 0; + + if (pud_none(pudval)) { + walk->action = ACTION_AGAIN; + return 0; + } + + /* Huge pud */ + walk->action = ACTION_CONTINUE; if (pud_trans_huge(pudval) || pud_devmap(pudval)) WARN_ON(pud_write(pudval) || pud_dirty(pudval)); -- 2.21.1