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Tue, 1 Sep 2020 06:38:44 +0000 (GMT) Received: from [9.85.87.76] (unknown [9.85.87.76]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 1 Sep 2020 06:38:44 +0000 (GMT) Subject: Re: [PATCH v3 09/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together To: Anshuman Khandual , 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> <20200827080438.315345-10-aneesh.kumar@linux.ibm.com> From: "Aneesh Kumar K.V" Message-ID: Date: Tue, 1 Sep 2020 12:08:43 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-01_04:2020-09-01,2020-09-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=2 priorityscore=1501 adultscore=0 mlxlogscore=999 phishscore=0 malwarescore=0 bulkscore=0 lowpriorityscore=0 spamscore=0 mlxscore=0 clxscore=1015 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009010054 X-Rspamd-Queue-Id: 1FD541AD1BA X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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 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)); -aneesh