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=unavailable 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 DC32AC433E2 for ; Tue, 1 Sep 2020 09:36:15 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3336E206CD for ; Tue, 1 Sep 2020 09:36:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3336E206CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4Bghlc32XNzDqWv for ; Tue, 1 Sep 2020 19:36:12 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=anshuman.khandual@arm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=arm.com Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4Bghj73pGrzDqNH for ; Tue, 1 Sep 2020 19:34:01 +1000 (AEST) 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 041D430E; Tue, 1 Sep 2020 02:34:00 -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 961733F71F; Tue, 1 Sep 2020 02:33:55 -0700 (PDT) Subject: Re: [PATCH v3 09/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together To: "Aneesh Kumar K.V" , linux-mm@kvack.org, akpm@linux-foundation.org References: <20200827080438.315345-1-aneesh.kumar@linux.ibm.com> <20200827080438.315345-10-aneesh.kumar@linux.ibm.com> From: Anshuman Khandual Message-ID: <9b75b175-f319-d40e-a95e-b323b3db654a@arm.com> Date: Tue, 1 Sep 2020 15:03:23 +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 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Christophe Leroy , x86@kernel.org, Mike Rapoport , Qian Cai , Gerald Schaefer , Vineet Gupta , linux-snps-arc@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 09/01/2020 12:08 PM, Aneesh Kumar K.V wrote: > On 9/1/20 9:11 AM, Anshuman Khandual wrote: >> >> >> On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote: >>> This will help in adding proper locks in a later patch >> >> It really makes sense to classify these tests here as static and dynamic. >> Static are the ones that test via page table entry values modification >> without changing anything on the actual page table itself. Where as the >> dynamic tests do change the page table. Static tests would probably never >> require any lock synchronization but the dynamic ones will do. >> >>> >>> Signed-off-by: Aneesh Kumar K.V >>> --- >>>   mm/debug_vm_pgtable.c | 52 ++++++++++++++++++++++++------------------- >>>   1 file changed, 29 insertions(+), 23 deletions(-) >>> >>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >>> index 0ce5c6a24c5b..78c8af3445ac 100644 >>> --- a/mm/debug_vm_pgtable.c >>> +++ b/mm/debug_vm_pgtable.c >>> @@ -992,7 +992,7 @@ static int __init debug_vm_pgtable(void) >>>       p4dp = p4d_alloc(mm, pgdp, vaddr); >>>       pudp = pud_alloc(mm, p4dp, vaddr); >>>       pmdp = pmd_alloc(mm, pudp, vaddr); >>> -    ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl); >>> +    ptep = pte_alloc_map(mm, pmdp, vaddr); >>>         /* >>>        * Save all the page table page addresses as the page table >>> @@ -1012,33 +1012,12 @@ static int __init debug_vm_pgtable(void) >>>       p4d_basic_tests(p4d_aligned, prot); >>>       pgd_basic_tests(pgd_aligned, prot); >>>   -    pte_clear_tests(mm, ptep, vaddr); >>> -    pmd_clear_tests(mm, pmdp); >>> -    pud_clear_tests(mm, pudp); >>> -    p4d_clear_tests(mm, p4dp); >>> -    pgd_clear_tests(mm, pgdp); >>> - >>> -    pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> -    pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot, saved_ptep); >>> -    pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot); >>> -    hugetlb_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> - >>>       pmd_leaf_tests(pmd_aligned, prot); >>>       pud_leaf_tests(pud_aligned, prot); >>>   -    pmd_huge_tests(pmdp, pmd_aligned, prot); >>> -    pud_huge_tests(pudp, pud_aligned, prot); >>> - >>>       pte_savedwrite_tests(pte_aligned, protnone); >>>       pmd_savedwrite_tests(pmd_aligned, protnone); >>>   -    pte_unmap_unlock(ptep, ptl); >>> - >>> -    pmd_populate_tests(mm, pmdp, saved_ptep); >>> -    pud_populate_tests(mm, pudp, saved_pmdp); >>> -    p4d_populate_tests(mm, p4dp, saved_pudp); >>> -    pgd_populate_tests(mm, pgdp, saved_p4dp); >>> - >>>       pte_special_tests(pte_aligned, prot); >>>       pte_protnone_tests(pte_aligned, protnone); >>>       pmd_protnone_tests(pmd_aligned, protnone); >>> @@ -1056,11 +1035,38 @@ static int __init debug_vm_pgtable(void) >>>       pmd_swap_tests(pmd_aligned, prot); >>>         swap_migration_tests(); >>> -    hugetlb_basic_tests(pte_aligned, prot); >>>         pmd_thp_tests(pmd_aligned, prot); >>>       pud_thp_tests(pud_aligned, prot); >>>   +    /* >>> +     * Page table modifying tests >>> +     */ >> >> In this comment, please do add some more details about how these tests >> need proper locking mechanism unlike the previous static ones. Also add >> a similar comment section for the static tests that dont really change >> page table and need not require corresponding locking mechanism. Both >> comment sections will make this classification clear. >> >>> +    pte_clear_tests(mm, ptep, vaddr); >>> +    pmd_clear_tests(mm, pmdp); >>> +    pud_clear_tests(mm, pudp); >>> +    p4d_clear_tests(mm, p4dp); >>> +    pgd_clear_tests(mm, pgdp); >>> + >>> +    ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl); >>> +    pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> +    pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot, saved_ptep); >>> +    pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot); >>> +    hugetlb_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> + >>> + >>> +    pmd_huge_tests(pmdp, pmd_aligned, prot); >>> +    pud_huge_tests(pudp, pud_aligned, prot); >>> + >>> +    pte_unmap_unlock(ptep, ptl); >>> + >>> +    pmd_populate_tests(mm, pmdp, saved_ptep); >>> +    pud_populate_tests(mm, pudp, saved_pmdp); >>> +    p4d_populate_tests(mm, p4dp, saved_pudp); >>> +    pgd_populate_tests(mm, pgdp, saved_p4dp); >>> + >>> +    hugetlb_basic_tests(pte_aligned, prot); >> >> hugetlb_basic_tests() is a non page table modifying static test and >> should be classified accordingly. >> >>> + >>>       p4d_free(mm, saved_p4dp); >>>       pud_free(mm, saved_pudp); >>>       pmd_free(mm, saved_pmdp); >>> >> >> Changes till this patch fails to boot on arm64 platform. This should be >> folded with the next patch. >> >> [   17.080644] ------------[ cut here ]------------ >> [   17.081342] kernel BUG at mm/pgtable-generic.c:164! >> [   17.082091] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >> [   17.082977] Modules linked in: >> [   17.083481] CPU: 79 PID: 1 Comm: swapper/0 Tainted: G        W         5.9.0-rc2-00105-g740e72cd6717 #14 >> [   17.084998] Hardware name: linux,dummy-virt (DT) >> [   17.085745] pstate: 60400005 (nZCv daif +PAN -UAO BTYPE=--) >> [   17.086645] pc : pgtable_trans_huge_deposit+0x58/0x60 >> [   17.087462] lr : debug_vm_pgtable+0x4dc/0x8f0 >> [   17.088168] sp : ffff80001219bcf0 >> [   17.088710] x29: ffff80001219bcf0 x28: ffff8000114ac000 >> [   17.089574] x27: ffff8000114ac000 x26: 0020000000000fd3 >> [   17.090431] x25: 0020000081400fd3 x24: fffffe00175c12c0 >> [   17.091286] x23: ffff0005df04d1a8 x22: 0000f18d6e035000 >> [   17.092143] x21: ffff0005dd790000 x20: ffff0005df18e1a8 >> [   17.093003] x19: ffff0005df04cb80 x18: 0000000000000014 >> [   17.093859] x17: 00000000b76667d0 x16: 00000000fd4e6611 >> [   17.094716] x15: 0000000000000001 x14: 0000000000000002 >> [   17.095572] x13: 000000000055d966 x12: fffffe001755e400 >> [   17.096429] x11: 0000000000000008 x10: ffff0005fcb6e210 >> [   17.097292] x9 : ffff0005fcb6e210 x8 : 0020000081590fd3 >> [   17.098149] x7 : ffff0005dd71e0c0 x6 : ffff0005df18e1a8 >> [   17.099006] x5 : 0020000081590fd3 x4 : 0020000081590fd3 >> [   17.099862] x3 : ffff0005df18e1a8 x2 : fffffe00175c12c0 >> [   17.100718] x1 : fffffe00175c1300 x0 : 0000000000000000 >> [   17.101583] Call trace: >> [   17.101993]  pgtable_trans_huge_deposit+0x58/0x60 >> [   17.102754]  do_one_initcall+0x74/0x1cc >> [   17.103381]  kernel_init_freeable+0x1d0/0x238 >> [   17.104089]  kernel_init+0x14/0x118 >> [   17.104658]  ret_from_fork+0x10/0x34 >> [   17.105251] Code: f9000443 f9000843 f9000822 d65f03c0 (d4210000) >> [   17.106303] ---[ end trace e63471e00f8c147f ]--- >> > > IIUC, this should happen even without the series right? This is > >     assert_spin_locked(pmd_lockptr(mm, pmdp)); Crash does not happen without this series. A previous patch [PATCH v3 08/13] added pgtable_trans_huge_deposit/withdraw() in pmd_advanced_tests(). arm64 does not define __HAVE_ARCH_PGTABLE_DEPOSIT and hence falls back on generic pgtable_trans_huge_deposit() which the asserts the lock.