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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 C988EC43603 for ; Wed, 18 Dec 2019 16:25:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8287A227BF for ; Wed, 18 Dec 2019 16:25:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8287A227BF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3B7968E0129; Wed, 18 Dec 2019 11:25:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 340278E00F5; Wed, 18 Dec 2019 11:25:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1BB4E8E0129; Wed, 18 Dec 2019 11:25:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0070.hostedemail.com [216.40.44.70]) by kanga.kvack.org (Postfix) with ESMTP id 01FD98E00F5 for ; Wed, 18 Dec 2019 11:25:03 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id B5EF11F0A for ; Wed, 18 Dec 2019 16:25:03 +0000 (UTC) X-FDA: 76278786486.11.ship84_2c27ec416ca16 X-HE-Tag: ship84_2c27ec416ca16 X-Filterd-Recvd-Size: 4363 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Dec 2019 16:25:03 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CD8BA31B; Wed, 18 Dec 2019 08:25:02 -0800 (PST) Received: from e112269-lin.arm.com (e112269-lin.cambridge.arm.com [10.1.196.56]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4C08C3F719; Wed, 18 Dec 2019 08:25:00 -0800 (PST) From: Steven Price To: Andrew Morton , linux-mm@kvack.org Cc: Steven Price , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Dave Hansen , Ingo Molnar , James Morse , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Peter Zijlstra , Thomas Gleixner , Will Deacon , x86@kernel.org, "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mark Rutland , "Liang, Kan" Subject: [PATCH v17 13/23] mm: pagewalk: Don't lock PTEs for walk_page_range_novma() Date: Wed, 18 Dec 2019 16:23:52 +0000 Message-Id: <20191218162402.45610-14-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191218162402.45610-1-steven.price@arm.com> References: <20191218162402.45610-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: walk_page_range_novma() can be used to walk page tables or the kernel or for firmware. These page tables may contain entries that are not backed by a struct page and so it isn't (in general) possible to take the PTE lock for the pte_entry() callback. So update walk_pte_range() to only take the lock when no_vma=3D=3Dfalse by splitting out the inner loop to a separate function and add a comment explaining the difference to walk_page_range_novma(). Signed-off-by: Steven Price --- mm/pagewalk.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index d5773465f6da..4b5ee92ba079 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -4,15 +4,12 @@ #include #include =20 -static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long = end, - struct mm_walk *walk) +static int walk_pte_range_inner(pte_t *pte, unsigned long addr, + unsigned long end, struct mm_walk *walk) { - pte_t *pte; - int err =3D 0; const struct mm_walk_ops *ops =3D walk->ops; - spinlock_t *ptl; + int err =3D 0; =20 - pte =3D pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (;;) { err =3D ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); if (err) @@ -22,8 +19,26 @@ static int walk_pte_range(pmd_t *pmd, unsigned long ad= dr, unsigned long end, break; pte++; } + return err; +} + +static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long = end, + struct mm_walk *walk) +{ + pte_t *pte; + int err =3D 0; + spinlock_t *ptl; + + if (walk->no_vma) { + pte =3D pte_offset_map(pmd, addr); + err =3D walk_pte_range_inner(pte, addr, end, walk); + pte_unmap(pte); + } else { + pte =3D pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + err =3D walk_pte_range_inner(pte, addr, end, walk); + pte_unmap_unlock(pte, ptl); + } =20 - pte_unmap_unlock(pte, ptl); return err; } =20 @@ -394,6 +409,12 @@ int walk_page_range(struct mm_struct *mm, unsigned l= ong start, return err; } =20 +/* + * Similar to walk_page_range() but can walk any page tables even if the= y are + * not backed by VMAs. Because 'unusual' entries may be walked this func= tion + * will also not lock the PTEs for the pte_entry() callback. This is use= ful for + * walking the kernel pages tables or page tables for firmware. + */ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private) --=20 2.20.1