Re: unhandlable pages

[Jane Chu <jane.chu@oracle.com>]

On 3/21/2022 2:07 PM, Yang Shi wrote:
> On Mon, Mar 21, 2022 at 10:28 AM Luck, Tony <tony.luck@intel.com> wrote:
>>
>> On Mon, Mar 21, 2022 at 05:21:05PM +0000, Matthew Wilcox wrote:
>>> On Mon, Mar 21, 2022 at 10:17:29AM -0700, Luck, Tony wrote:
>>>> Validation folks are seeing this on a v5.16 kernel. I don't
>>>> see any changes in v5.17 that look like they address it.
>>>>
>>>> Mar 04 14:05:05 JF5300-07B181T kernel: page:00000000696b0b6a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x195cda44
>>>> Mar 04 14:05:05 JF5300-07B181T kernel: flags: 0x57ffffc0801000(reserved|hwpoison|node=1|zone=2|lastcpupid=0x1fffff)
>>>> Mar 04 14:05:05 JF5300-07B181T kernel: raw: 0057ffffc0801000 ffff6ea817369108 ffff6ea817369108 0000000000000000
>>>> Mar 04 14:05:05 JF5300-07B181T kernel: raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
>>>> Mar 04 14:05:05 JF5300-07B181T kernel: page dumped because: hwpoison: unhandlable page
>>>> Mar 04 14:05:05 JF5300-07B181T kernel: Memory failure: 0x195cda44: recovery action for unknown page: Ignored
>>>>
>>>> Som debugging shows this is an anon page (expected ... that's the
>>>> type of page where the error was injected. They see shake_page()
>>>> called three times, but it doesn't change anything, so the page
>>>> is reported as unhandlable.
>>>
>>> Uhm, that's not PageAnon.  page->mapping is NULL, and anon pages have
>>> the bottom bit set with the rest of the page->mapping pointing to its
>>> anon_vma.  Why do you think it's an anon page?
>>
>> Sorry. I didn't do that decode ... just copied what was in the internal
>> report.  If it isn't anon, then does that page dump give info on what
>> type the page is?
> 
> As Willy said we can't tell what type the page is. Per the dumped
> information, the page has:
>    - 1 refcount, likely get from hwpoison
>    - 0 mapcount, unmapped and not unmapped by hwpoison since
> dump_page() is called before that,
>    - NULL mapping
>    - PG_reserved flag is set and no other flag is set
> 
> So I just can say it is very unlikely to be an anonymous page. It is
> not slab either. And neither anonymous/page cache nor slab should be
> reserved flag set, so it should be some other types.

Tony,

Agreed with Matthew, it might have been a device page.
So we have pfn:0x195cda44, does /proc/iomem leave any clue?

thanks,
-jane


> 
>>
>> -Tony
>