From: Anshuman Khandual <anshuman.khandual@arm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
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 <gerald.schaefer@de.ibm.com>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Vineet Gupta <vgupta@synopsys.com>,
Mike Rapoport <rppt@linux.ibm.com>, Qian Cai <cai@lca.pw>
Subject: Re: [PATCH v3 09/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together
Date: Tue, 1 Sep 2020 15:03:23 +0530 [thread overview]
Message-ID: <9b75b175-f319-d40e-a95e-b323b3db654a@arm.com> (raw)
In-Reply-To: <b6240372-4554-8c17-186a-cdc0b0a9089c@linux.ibm.com>
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 <aneesh.kumar@linux.ibm.com>
>>> ---
>>> 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.
next prev parent reply other threads:[~2020-09-01 9:34 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 8:04 [PATCH v3 00/13] mm/debug_vm_pgtable fixes Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 01/13] powerpc/mm: Add DEBUG_VM WARN for pmd_clear Aneesh Kumar K.V
2020-09-01 3:12 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 02/13] powerpc/mm: Move setting pte specific flags to pfn_pte Aneesh Kumar K.V
2020-09-01 3:13 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value Aneesh Kumar K.V
2020-09-01 3:15 ` Anshuman Khandual
2020-09-01 6:21 ` Aneesh Kumar K.V
2020-09-01 7:32 ` Anshuman Khandual
2020-09-01 7:36 ` Aneesh Kumar K.V
2020-09-01 7:46 ` Anshuman Khandual
2020-09-01 7:55 ` Aneesh Kumar K.V
2020-09-02 3:45 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 04/13] mm/debug_vm_pgtables/hugevmap: Use the arch helper to identify huge vmap support Aneesh Kumar K.V
2020-09-01 3:16 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 05/13] mm/debug_vm_pgtable/savedwrite: Enable savedwrite test with CONFIG_NUMA_BALANCING Aneesh Kumar K.V
2020-09-01 3:18 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 06/13] mm/debug_vm_pgtable/THP: Mark the pte entry huge before using set_pmd/pud_at Aneesh Kumar K.V
2020-09-01 3:21 ` Anshuman Khandual
2020-09-01 6:23 ` Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 08/13] mm/debug_vm_pgtable/thp: Use page table depost/withdraw with THP Aneesh Kumar K.V
2020-09-01 3:22 ` Anshuman Khandual
2020-09-01 6:25 ` Aneesh Kumar K.V
2020-09-01 6:50 ` Christophe Leroy
2020-09-01 7:40 ` Aneesh Kumar K.V
2020-09-01 7:51 ` Christophe Leroy
2020-09-02 3:45 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 09/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together Aneesh Kumar K.V
2020-09-01 3:41 ` Anshuman Khandual
2020-09-01 6:38 ` Aneesh Kumar K.V
2020-09-01 9:33 ` Anshuman Khandual [this message]
2020-09-01 9:36 ` Aneesh Kumar K.V
2020-09-01 9:58 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 10/13] mm/debug_vm_pgtable/locks: Take correct page table lock Aneesh Kumar K.V
2020-09-01 3:44 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 11/13] mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 12/13] mm/debug_vm_pgtable/hugetlb: Disable hugetlb test on ppc64 Aneesh Kumar K.V
2020-09-01 4:03 ` Anshuman Khandual
2020-09-01 6:30 ` Aneesh Kumar K.V
2020-09-01 7:59 ` Christophe Leroy
2020-09-02 13:05 ` Anshuman Khandual
2020-09-02 13:20 ` Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 13/13] mm/debug_vm_pgtable: populate a pte entry before fetching it Aneesh Kumar K.V
2020-08-27 12:17 ` kernel test robot
2020-09-01 3:25 ` Anshuman Khandual
2020-09-01 6:37 ` Aneesh Kumar K.V
2020-09-01 7:38 ` Anshuman Khandual
2020-09-01 9:58 ` Aneesh Kumar K.V
2020-09-02 3:49 ` Anshuman Khandual
2020-09-02 3:58 ` Aneesh Kumar K.V
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