Re: [PATCH] Revert "mm/page_isolation: unset migratetype directly for non Buddy page"

[Thorsten Leemhuis <regressions@leemhuis.info>]

For the record:

#regzbot fixed-by: a85468b766d3bc17c8b17ed23a36ef6469340bb2

On 30.01.22 10:24, Thorsten Leemhuis wrote:
> Hi, this is your Linux kernel regression tracker speaking.
> 
> On 26.01.22 03:18, Chen Wandun wrote:
>> 在 2022/1/26 0:40, Vlastimil Babka 写道:
>>> On 1/17/22 15:27, Chen Wandun wrote:
>>>> This reverts commit 075782149abff45ee22f27315eced44d02b96779.
>>>>
>>>> commit 075782149abf ("mm/page_isolation: unset migratetype directly for
>>> That's an old -next commit id, it went to mainline as 721fb891ad0b
>>> ("mm/page_isolation: unset migratetype directly for non Buddy page")
>>>
>>>> non Buddy page") will result memory that should in buddy disappear by
>>>> mistake. move_freepages_block move all pages in pageblock instead of
>>>> pages indicated by input parameter, so if input pages is not in buddy
>>>> but other pages in pageblock is in buddy, it will result in page out of
>>>> control.
>>>>
>>>> Reported-by: "kernelci.org bot" <bot@kernelci.org>
>>>> Signed-off-by: Chen Wandun <chenwandun@huawei.com>
>>> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>>>
>>> #regzbot ^introduced: 721fb891ad0b
> 
> Thx for getting regzbot involved, much appreciated.
> 
>>> There should better be also:
>>>
>>> Fixes: 721fb891ad0b ("mm/page_isolation: unset migratetype directly
>>> for non
>>> Buddy page")
>>>
>>> Especially as that commit had a (inadequate, IMHO, for an optimization)
>>> Fixes: tag and could end up being backported somewhere without the
>>> followup
>>> fix/revert.
>>
>> thanks, I will send v2
> 
> Just wondering:
> 
> Andrew, I don't see this patch in the list of changes you sent to Linus
> yesterday. Shouldn't it be in there due to above reason alone? And there
> is another reason: it seems to be an issue people actually hit, as
> Guenter mentioned in this thread. It thus complicates things for those
> that want to help testing pre-releases.
> 
> Or am I missing something/asking too much in this case?
> 
> BTW, let's tell regzbot about v2:
> 
> #regzbot monitor:
> https://lore.kernel.org/all/20220126024436.13921-1-chenwandun@huawei.com/
> 
> Ciao, Thorsten
> 
>>>> ---
>>>>   mm/page_isolation.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
>>>> index 6a0ddda6b3c5..f67c4c70f17f 100644
>>>> --- a/mm/page_isolation.c
>>>> +++ b/mm/page_isolation.c
>>>> @@ -115,7 +115,7 @@ static void unset_migratetype_isolate(struct page
>>>> *page, unsigned migratetype)
>>>>        * onlining - just onlined memory won't immediately be
>>>> considered for
>>>>        * allocation.
>>>>        */
>>>> -    if (!isolated_page && PageBuddy(page)) {
>>>> +    if (!isolated_page) {
>>>>           nr_pages = move_freepages_block(zone, page, migratetype,
>>>> NULL);
>>>>           __mod_zone_freepage_state(zone, nr_pages, migratetype);
>>>>       }
>>> .
>>
>>
>>
>