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=-13.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 86462C433E7 for ; Tue, 1 Sep 2020 07:38:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3B4CF206CD for ; Tue, 1 Sep 2020 07:38:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3B4CF206CD 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 B2D8B6B0003; Tue, 1 Sep 2020 03:38:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ADE726B0037; Tue, 1 Sep 2020 03:38:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9F4B96B0055; Tue, 1 Sep 2020 03:38:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0219.hostedemail.com [216.40.44.219]) by kanga.kvack.org (Postfix) with ESMTP id 893DB6B0003 for ; Tue, 1 Sep 2020 03:38:46 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 53E218248068 for ; Tue, 1 Sep 2020 07:38:46 +0000 (UTC) X-FDA: 77213690652.22.hair93_3f134c027096 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 222D018038E67 for ; Tue, 1 Sep 2020 07:38:46 +0000 (UTC) X-HE-Tag: hair93_3f134c027096 X-Filterd-Recvd-Size: 4402 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Tue, 1 Sep 2020 07:38:45 +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 D8F5A1FB; Tue, 1 Sep 2020 00:38:44 -0700 (PDT) Received: from [10.163.69.134] (unknown [10.163.69.134]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9A3663F71F; Tue, 1 Sep 2020 00:38:40 -0700 (PDT) Subject: Re: [PATCH v3 13/13] mm/debug_vm_pgtable: populate a pte entry before fetching it To: "Aneesh Kumar K.V" , linux-mm@kvack.org, akpm@linux-foundation.org Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-snps-arc@lists.infradead.org, x86@kernel.org, linux-arch@vger.kernel.org, Gerald Schaefer , Christophe Leroy , Vineet Gupta , Mike Rapoport , Qian Cai References: <20200827080438.315345-1-aneesh.kumar@linux.ibm.com> <20200827080438.315345-14-aneesh.kumar@linux.ibm.com> From: Anshuman Khandual Message-ID: Date: Tue, 1 Sep 2020 13:08:08 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Rspamd-Queue-Id: 222D018038E67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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: On 09/01/2020 12:07 PM, Aneesh Kumar K.V wrote: > On 9/1/20 8:55 AM, Anshuman Khandual wrote: >> >> >> On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote: >>> pte_clear_tests operate on an existing pte entry. Make sure that is n= ot a none >>> pte entry. >>> >>> Signed-off-by: Aneesh Kumar K.V >>> --- >>> =C2=A0 mm/debug_vm_pgtable.c | 6 ++++-- >>> =C2=A0 1 file changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >>> index 21329c7d672f..8527ebb75f2c 100644 >>> --- a/mm/debug_vm_pgtable.c >>> +++ b/mm/debug_vm_pgtable.c >>> @@ -546,7 +546,7 @@ static void __init pgd_populate_tests(struct mm_s= truct *mm, pgd_t *pgdp, >>> =C2=A0 static void __init pte_clear_tests(struct mm_struct *mm, pte_t= *ptep, >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long vaddr) >>> =C2=A0 { >>> -=C2=A0=C2=A0=C2=A0 pte_t pte =3D ptep_get(ptep); >>> +=C2=A0=C2=A0=C2=A0 pte_t pte =3D=C2=A0 ptep_get_and_clear(mm, vaddr,= ptep); >> >> Seems like ptep_get_and_clear() here just clears the entry in preparat= ion >> for a following set_pte_at() which otherwise would have been a problem= on >> ppc64 as you had pointed out earlier i.e set_pte_at() should not updat= e an >> existing valid entry. So the commit message here is bit misleading. >> >=20 > and also fetch the pte value which is used further. >=20 >=20 >>> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pr_debug("Validating PTE clear\= n"); >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pte =3D __pte(pte_val(pte) | RANDOM_OR= VALUE); >>> @@ -944,7 +944,7 @@ static int __init debug_vm_pgtable(void) >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 p4d_t *p4dp, *saved_p4dp; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pud_t *pudp, *saved_pudp; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pmd_t *pmdp, *saved_pmdp, pmd; >>> -=C2=A0=C2=A0=C2=A0 pte_t *ptep; >>> +=C2=A0=C2=A0=C2=A0 pte_t *ptep, pte; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgtable_t saved_ptep; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgprot_t prot, protnone; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 phys_addr_t paddr; >>> @@ -1049,6 +1049,8 @@ static int __init debug_vm_pgtable(void) >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >>> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ptep =3D pte_alloc_map_lock(mm,= pmdp, vaddr, &ptl); >>> +=C2=A0=C2=A0=C2=A0 pte =3D pfn_pte(pte_aligned, prot); >>> +=C2=A0=C2=A0=C2=A0 set_pte_at(mm, vaddr, ptep, pte); >> >> Not here, creating and populating an entry must be done in respective >> test functions itself. Besides, this seems bit redundant as well. The >> test pte_clear_tests() with the above change added, already >> >> - Clears the PTEP entry with ptep_get_and_clear() >=20 > and fetch the old value set previously. In that case, please move above two lines i.e pte =3D pfn_pte(pte_aligned, prot); set_pte_at(mm, vaddr, ptep, pte); from debug_vm_pgtable() to pte_clear_tests() and update it's arguments as required.