Re: [PATCH STABLE v6.1.y] mm/migrate: set swap entry values of THP tail pages properly.

[Zi Yan <ziy@nvidia.com>]

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On 5 Mar 2024, at 11:22, Charan Teja Kalla wrote:

> Thanks David for various inputs on this patch!!.
>
> On 3/5/2024 9:47 PM, Zi Yan wrote:
>> On 5 Mar 2024, at 11:13, Zi Yan wrote:
>>
>>> From: Zi Yan <ziy@nvidia.com>
>>>
>>> The tail pages in a THP can have swap entry information stored in their
>>> private field. When migrating to a new page, all tail pages of the new
>>> page need to update ->private to avoid future data corruption.
>>
>> Corresponding swapcache entries need to be updated as well.
>> e71769ae5260 ("mm: enable thp migration for shmem thp") fixed it already.
>>
>> Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")
>>
>
> Thanks Zi Yan, for posting this patch. I think below tag too applicable?
>
> Closes:
> https://lore.kernel.org/linux-mm/1707814102-22682-1-git-send-email-quic_charante@quicinc.com/

Right. Let me add it to other stable fixes I am going to send.


Hi Greg,

Could you add the information above (text, Fixes, and Closes) to this patch?
Or do you want me to resend?

Thanks.

>
>>
>>>
>>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>>> ---
>>>  mm/migrate.c | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/mm/migrate.c b/mm/migrate.c
>>> index c93dd6a31c31..c5968021fde0 100644
>>> --- a/mm/migrate.c
>>> +++ b/mm/migrate.c
>>> @@ -423,8 +423,12 @@ int folio_migrate_mapping(struct address_space *mapping,
>>>  	if (folio_test_swapbacked(folio)) {
>>>  		__folio_set_swapbacked(newfolio);
>>>  		if (folio_test_swapcache(folio)) {
>>> +			int i;
>>> +
>>>  			folio_set_swapcache(newfolio);
>>> -			newfolio->private = folio_get_private(folio);
>>> +			for (i = 0; i < nr; i++)
>>> +				set_page_private(folio_page(newfolio, i),
>>> +					page_private(folio_page(folio, i)));
>>>  		}
>>>  		entries = nr;
>>>  	} else {
>>> -- 
>>> 2.43.0
>>
>>
>> --
>> Best Regards,
>> Yan, Zi


--
Best Regards,
Yan, Zi

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