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Subject: Re: [PATCH v2] mm/memory-failure: fix crash in
 split_huge_page_to_list from soft_offline_page
To: Matthew Wilcox <willy@infradead.org>
CC: <naoya.horiguchi@nec.com>, <akpm@linux-foundation.org>,
	<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
References: <20240124084014.1772906-1-linmiaohe@huawei.com>
 <ZbENgT-2dZHQQ90h@casper.infradead.org>
 <6d3f4822-8bc1-1551-b088-0a6d4c13f049@huawei.com>
 <ZbJursWt9Hp9kXac@casper.infradead.org>
From: Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <f548c1d5-5bd5-a7cd-ae59-ba7a59540a19@huawei.com>
Date: Fri, 26 Jan 2024 09:13:51 +0800
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On 2024/1/25 22:22, Matthew Wilcox wrote:
> On Thu, Jan 25, 2024 at 07:53:25PM +0800, Miaohe Lin wrote:
>> On 2024/1/24 21:15, Matthew Wilcox wrote:
>>>>   Call Trace:
>>>>    <TASK>
>>>>    ? die+0x32/0x90
>>>>    ? do_trap+0xde/0x110
>>>>    ? folio_memcg+0xaf/0xd0
>>>>    ? do_error_trap+0x60/0x80
>>>>    ? folio_memcg+0xaf/0xd0
>>>>    ? exc_invalid_op+0x53/0x70
>>>>    ? folio_memcg+0xaf/0xd0
>>>>    ? asm_exc_invalid_op+0x1a/0x20
>>>>    ? folio_memcg+0xaf/0xd0
>>>>    ? folio_memcg+0xae/0xd0
>>>
>>> I might trim these ? lines out of the backtrace ...
>>
>> Do you mean make backtrace looks like something below?
>>
>> Call Trace:
>>  <TASK>
>>  split_huge_page_to_list+0x4d/0x1380
>>  ? sysvec_apic_timer_interrupt+0xf/0x80
>>  try_to_split_thp_page+0x3a/0xf0
>>  soft_offline_page+0x1ea/0x8a0
>>  soft_offline_page_store+0x52/0x90
>>  kernfs_fop_write_iter+0x118/0x1b0
>>  vfs_write+0x30b/0x430
>>  ksys_write+0x5e/0xe0
>>  do_syscall_64+0xb0/0x1b0
>>  entry_SYSCALL_64_after_hwframe+0x6d/0x75
>> RIP: 0033:0x7f6c60d14697
> 
> Yes.  I'd trim the sysvec_apic_timer_interrupt+0xf/0x80 line too.
> These lines aren't actually part of the call trace.  They're addresses
> that the unwinder found on the stack but don't actually fit the call
> trace.  It puts them in in case they're helpful, but marks them with a ?
> to indicate that they're probably not part of the call trace.

I see. Many thanks for your explanation. Will update backtrace in next version.

Thanks.