Re: [RFC PATCH] PM / hibernate: make sure each resuming page is in current memory zones

[chenyu5 <yu.c.chen@intel.com>]

On 2015年07月16日 08:30, Rafael J. Wysocki wrote:
> On Monday, July 06, 2015 04:37:39 PM joeyli wrote:
>> Hi Chen Yu,
>>
>> On Thu, Jul 02, 2015 at 04:00:42PM +0800, chenyu5 wrote:
>>> Hi, Joey
>>> thanks for your reply,
>>>
>>> On 2015年07月02日 14:19, joeyli wrote:
>>>> Hi Chen Yu,
>>>>
>>>> On Tue, Jun 30, 2015 at 11:54:28PM +0800, Chen Yu wrote:
>>>>> Commit 84c91b7ae07c ("PM / hibernate: avoid unsafe pages in e820 reserved
>>>>> regions") was reverted, because this patch makes resume from hibernation
>>>>> on Lenovo x230 unreliable. But reverting may bring back the kernel
>>>>> exception firstly reported in former patch. In general, there are three
>>>>> problems in current code when resuming from hibernation:
>>>>>
>>>>> 1.Resuming page may also be in second kernel's e820 reserved region.
>>>>> BIOS-e820: [mem 0x0000000069d4f000-0x0000000069e12fff] reserved
>>>>> this causes kernel exception described in Commit 84c91b7ae07c
>>>>> ("PM / hibernate: avoid unsafe pages in e820 reserved regions")
>>>>>
>>>>> 2.If Commit 84c91b7ae07c ("PM / hibernate: avoid unsafe pages in e820
>>>>> reserved regions") is applied to fix problem 1, and if E820_RESERVED_KERN
>>>>> regions causes some regions at e820 table not page aligned,
>>>>> e820_mark_nosave_regions will misjudgment the non-page aligned space to
>>>>> be "hole" space and add to nosave regions, this causes resuming failed.
>>>>> Refer to https://bugzilla.kernel.org/show_bug.cgi?id=96111 for detail.
>>>>>
>>>>
>>>> Sorry for I am not fully understand why checking pfn_valid could avoid
>>>> the above 2. issue?
>>>>
>>> [Yu] According to e820_mark_nosave_regions, two kinds of e820
>>> regions will be regarded as nosave:
>>> a.e820.map holes between each e820entry
>>> b.e820entry with (!E820_RAM && !E820_RESERVED_KERN)
>>> dmesg in
>>> https://bugzilla.kernel.org/show_bug.cgi?id=96111
>>> shows that:
>>>
>>> BIOS-e820: [mem 0x000000005baff000-0x00000000d684ffff] usable
>>> reserve setup_data: [mem 0x000000009d3e0018-0x000000009d3f0057] usable
>>> PM: Registered nosave memory: [mem 0x9d3e0000-0x9d3e0fff]
>>>
>>> e820 map was changed by situation a, but it should not be added to
>>> nosave list, right?
>>>
>>> and according to saveable_page, only pages in the zone will be saved:
>>> if (page_zone(page_ != zone)
>>> 	return NULL;
>>>
>>> The function of is_valid_orig_page in this patch treats setup_data as
>>> valid page, so I think this workaround issue 2.
>>>
>>>
>>>> Per my understood should waiting Yinghai Lu's patches for killing
>>>> E820_RESERVED_KERN to avoid the aligned problem.
>>> [Yu] yes, it is a graceful solution, but I don't see that in 4.1? And
>>> we encountered problem 3 in our testing enviroment, so I wrote a patch
>>> to deal with it first.
>>>>
>>>>
>>>> Thanks a lot!
>>>> Joey Lee
>>>>
>>
>> Thanks for your explanation, then your patch makes sense to me.
>>
>> Please feel free to add tag:
>>
>> Reviewed-by: Lee, Chun-Yi <joeyli.kernel@gmail.com>
>
> Patch queued up for 4.3, thanks!
>
Hi Rafeal,
Please help drop this patch for now, QA has
found some problems with this patch applied,
we're working on it now. Sorry for inconvenience.
Regards,
Yu