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Date: Wed, 23 Sep 2020 08:34:52 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
kernel test robot <rong.a.chen@...el.com>
Cc: Stephen Rothwell <sfr@...b.auug.org.au>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Michael Ellerman <mpe@...erman.id.au>,
Andrew Morton <akpm@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
lkp@...el.com
Subject: Re: [mm/debug_vm_pgtable/locks] e2aad6f1d2:
BUG:unable_to_handle_page_fault_for_address
On 09/22/2020 02:50 PM, Aneesh Kumar K.V wrote:
> On 9/22/20 2:22 PM, Anshuman Khandual wrote:
>>
>>
>> On 09/22/2020 09:33 AM, Aneesh Kumar K.V wrote:
>>> On 9/21/20 2:51 PM, kernel test robot wrote:
>>>> Greeting,
>>>>
>>>> FYI, we noticed the following commit (built with gcc-9):
>>>>
>>>> commit: e2aad6f1d232b457ea6a3194992dd4c0a83534a5 ("mm/debug_vm_pgtable/locks: take correct page table lock")
>>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>>>>
>>>>
>>>> in testcase: trinity
>>>> version: trinity-i386
>>>> with following parameters:
>>>>
>>>> ����runtime: 300s
>>>>
>>>> test-description: Trinity is a linux system call fuzz tester.
>>>> test-url: http://codemonkey.org.uk/projects/trinity/
>>>>
>>>>
>>>> on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G
>>>>
>>>> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>>>>
>>>>
>>>> +----------------------------------------------------------------------+------------+------------+
>>>> |��������������������������������������������������������������������� | c50eb1ed65 | e2aad6f1d2 |
>>>> +----------------------------------------------------------------------+------------+------------+
>>>> | boot_successes������������������������������������������������������ | 0��������� | 0��������� |
>>>> | boot_failures������������������������������������������������������� | 61�������� | 17�������� |
>>>> | BUG:workqueue_lockup-pool������������������������������������������� | 1��������� |����������� |
>>>> | BUG:sleeping_function_called_from_invalid_context_at_mm/page_alloc.c | 60�������� | 17�������� |
>>>> | BUG:unable_to_handle_page_fault_for_address������������������������� | 0��������� | 17�������� |
>>>> | Oops:#[##]���������������������������������������������������������� | 0��������� | 17�������� |
>>>> | EIP:ptep_get�������������������������������������������������������� | 0��������� | 17�������� |
>>>> | Kernel_panic-not_syncing:Fatal_exception���������������������������� | 0��������� | 17�������� |
>>>> +----------------------------------------------------------------------+------------+------------+
>>>>
>>>>
>>>> If you fix the issue, kindly add following tag
>>>> Reported-by: kernel test robot <rong.a.chen@...el.com>
>>>>
>>>>
>>>> [�� 28.726464] BUG: sleeping function called from invalid context at mm/page_alloc.c:4822
>>>> [�� 28.727835] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper
>>>> [�� 28.729221] no locks held by swapper/1.
>>>> [�� 28.729954] CPU: 0 PID: 1 Comm: swapper Not tainted 5.9.0-rc3-00324-ge2aad6f1d232b4 #1
>>>> [�� 28.731484] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
>>>> [�� 28.732891] Call Trace:
>>>> [�� 28.733295]� ? show_stack+0x48/0x50
>>>> [�� 28.733943]� dump_stack+0x1b/0x1d
>>>> [�� 28.734569]� ___might_sleep+0x205/0x219
>>>> [�� 28.735292]� __might_sleep+0x106/0x10f
>>>> [�� 28.736022]� __alloc_pages_nodemask+0xe0/0x2c8
>>>> [�� 28.736845]� swap_migration_tests+0x62/0x295
>>>> [�� 28.737639]� debug_vm_pgtable+0x587/0x9b5
>>>> [�� 28.738374]� ? pte_advanced_tests+0x267/0x267
>>>> [�� 28.739318]� do_one_initcall+0x129/0x31c
>>>> [�� 28.740023]� ? rcu_read_lock_sched_held+0x46/0x74
>>>> [�� 28.740944]� kernel_init_freeable+0x201/0x250
>>>> [�� 28.741763]� ? rest_init+0xf8/0xf8
>>>> [�� 28.742401]� kernel_init+0xe/0x15d
>>>> [�� 28.743040]� ? rest_init+0xf8/0xf8
>>>> [�� 28.743694]� ret_from_fork+0x1c/0x30
>>>
>>>
>>> This should be fixed by
>>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/mm/debug_vm_pgtable.c?id=3a4f9a45eadb6ed5fc04686e8db4dc7bb1caec44
>>>
>>>> [�� 28.744364] BUG: unable to handle page fault for address: fffbbea4
>>>> [�� 28.745465] #PF: supervisor read access in kernel mode
>>>> [�� 28.746373] #PF: error_code(0x0000) - not-present page
>>>> [�� 28.747275] *pde = 0492b067 *pte = 00000000
>>>> [�� 28.748054] Oops: 0000 [#1]
>>>> [�� 28.748548] CPU: 0 PID: 1 Comm: swapper Tainted: G������� W�������� 5.9.0-rc3-00324-ge2aad6f1d232b4 #1
>>>> [�� 28.750188] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
>>>> [�� 28.751641] EIP: ptep_get+0x0/0x3
>>>> [�� 28.752226] Code: 5d fc c9 c3 55 c1 e8 1a 89 e5 53 31 db 83 f8 1f 6a 00 0f 94 c3 b8 80 67 02 c4 31 c9 89 da e8 16 5c f1 ff 89 d8 8b 5d fc c9 c3 <8b> 00 c3 55 31 c9 89 e5 57 56 53 8b 70 04 89 c3 b8 10 68 02 c4 6a
>>>> [�� 28.755465] EAX: fffbbea4 EBX: fffbbea4 ECX: 000047bd EDX: fffbbea4
>>>> [�� 28.756418] ESI: 000047bd EDI: 00000025 EBP: f406bed8 ESP: f406bebc
>>>> [�� 28.757522] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010286
>>>> [�� 28.758739] CR0: 80050033 CR2: fffbbea4 CR3: 04928000 CR4: 000406d0
>>>> [�� 28.759828] Call Trace:
>>>> [�� 28.760235]� ? hugetlb_advanced_tests+0x2a/0x27f
>>>> [�� 28.761099]� ? do_raw_spin_unlock+0xd7/0x112
>>>> [�� 28.761872]� debug_vm_pgtable+0x927/0x9b5
>>>> [�� 28.762578]� ? pte_advanced_tests+0x267/0x267
>>>> [�� 28.763462]� do_one_initcall+0x129/0x31c
>>>> [�� 28.764134]� ? rcu_read_lock_sched_held+0x46/0x74
>>>> [�� 28.764948]� kernel_init_freeable+0x201/0x250
>>>> [�� 28.765654]� ? rest_init+0xf8/0xf8
>>>> [�� 28.766277]� kernel_init+0xe/0x15d
>>>> [�� 28.766878]� ? rest_init+0xf8/0xf8
>>>> [�� 28.767488]� ret_from_fork+0x1c/0x30
>>>> [�� 28.768052] Modules linked in:
>>>> [�� 28.768532] CR2: 00000000fffbbea4
>>>> [�� 28.769065] ---[ end trace 9c4395cf49c7b3e7 ]---
>>>>
>>>
>>> IIUC, Anshuman is reworking the test to follow the page table update rules.
>>
>> The failure here has been attributed to this particular patch, and
>> IIRC we did not see this particular failure before this series.
>>
>
> IIUC that crash is because the usage of pte_t pointer. With highmem that address is unmapped earlier with the series as expected. But hugetlb_advanced_test is wrongly using that pointer instead of using a pte_t * that should be allocated by huge_pte_alloc().
Hence, now it does not really make sense to keep hugetlb_advanced_test()
test and create this regression on i386. Will probably send a patch to
drop this test altogether for now.
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