Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup

[Alex Shi]

在 2020/8/13 下午2:20, Michal Hocko 写道:
> On Wed 12-08-20 11:25:53, Alex Shi wrote:
>> >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001
>> From: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
>> Date: Wed, 5 Aug 2020 21:02:30 +0800
>> Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when memcg
>>  is disabled
>>
>> If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL
>> and so the charge is skipped and that will trigger a warning like below.
>> Let's return from the funcs earlier.
>>
>>  ---[ end trace f1f34bfc3b32ed2f ]---
>>  anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked)
>>  raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1
>>  raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000
>>  page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg)
> 
> Yes this is better. It would be even more informative if you added the
> backtrace.

The stack is a bit long.
I still don't know where cause the asm_exc_page_fault? And seems the vma is from
kernel not user.