Re: [PATCH v4 1/4] mm/rmap: duplicate a PMD mapping as one in folio_dup_file_rmap_pmd()

[Konstantin Khorenko <khorenko@virtuozzo.com>]

On 10/22/26 14:11, Lorenzo Stoakes (ARM) wrote:
...
>>
>> Both functions were introduced in a single commit, i think it's a simple copy-paste issue.
>>
>> The helper never had a caller, so nobody could hit it. If you prefer, I
>> can drop the Fixes tag and only mention d8ef5e311d7b in the changelog, as
>> there is nothing to backport.
> 
> I mean, it seems like a bug to me? If there's no harm in backporting it I think you
> should add Cc: stable@vger.kernel.org in that case actually.

Nobody ever called this helper till the patch
   "mm/huge_memory: copy file THPs at fork like copy_present_ptes() does"

in the current series, so there is no actual bug to fix in stables,
so may be not to add extra work to stable trees maintainers?

The other question is: what to do with the actual bug this series is addressed to.
i don't think the significant rewrite of PMD handling is a good patch for stable,
so may be we'll need to create a minimal fix like my 1st version to fix
the existing problem - especially for stable trees.
Or may be not to fix stables at all.

But let's first finish with the proper fix/rewrite. One problem a time to solve.

--
Cheers, Konstantin