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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Anshuman Khandual <anshuman.khandual@arm.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 12:08:43 +0530	[thread overview]
Message-ID: <b6240372-4554-8c17-186a-cdc0b0a9089c@linux.ibm.com> (raw)
In-Reply-To: <d0a0a50c-702b-c63a-edf2-263e4e7bd4a5@arm.com>

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));


-aneesh


  reply	other threads:[~2020-09-01  6:39 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 [this message]
2020-09-01  9:33       ` Anshuman Khandual
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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