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

Charan Teja Kalla
2024-03-05T16:22:52Z

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/

>
>>
>> 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