Re: [PATCH 0/4] mm/filemap: Limit page cache size to that supported by xarray

[Gavin Shan <gshan@redhat.com>]

On 6/26/24 5:05 AM, David Hildenbrand wrote:
> On 25.06.24 20:58, Andrew Morton wrote:
>> On Tue, 25 Jun 2024 20:51:13 +0200 David Hildenbrand <david@redhat.com> wrote:
>>
>>>> I could split them and feed 1&2 into 6.10-rcX and 3&4 into 6.11-rc1.  A
>>>> problem with this approach is that we're putting a basically untested
>>>> combination into -stable: 1&2 might have bugs which were accidentally
>>>> fixed in 3&4.  A way to avoid this is to add cc:stable to all four
>>>> patches.
>>>>
>>>> What are your thoughts on this matter?
>>>
>>> Especially 4 should also be CC stable, so likely we should just do it
>>> for all of them.
>>
>> Fine.  A Fixes: for 3 & 4 would be good.  Otherwise we're potentially
>> asking for those to be backported further than 1 & 2, which seems
>> wrong.
> 
> 4 is shmem fix, which likely dates back a bit longer.
> 
>>
>> Then again, by having different Fixes: in the various patches we're
>> suggesting that people split the patch series apart as they slot things
>> into the indicated places.  In other words, it's not a patch series at
>> all - it's a sprinkle of independent fixes.  Are we OK thinking of it
>> in that fashion?
> 
> The common themes is "pagecache cannot handle > order-11", #1-3 tackle "ordinary" file THP, #4 tackles shmem THP.
> 
> So I'm not sure we should be splitting it apart. It's just that shmem THP arrived before file THP :)
> 

I rechecked the history, it's a bit hard to have precise fix tag for PATCH[4].
Please let me know if you have a better one for PATCH[4].

#4
   Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
   Cc: stable@kernel.org # v4.10+
   Fixes: 552446a41661 ("shmem: Convert shmem_add_to_page_cache to XArray")
   Cc: stable@kernel.org # v4.20+
#3
   Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
   Cc: stable@kernel.org # v5.18+
#2
   Fixes: 4687fdbb805a ("mm/filemap: Support VM_HUGEPAGE for file mappings")
   Cc: stable@kernel.org # v5.18+
#1
   Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
   Cc: stable@kernel.org # v5.18+

I probably need to move PATCH[3] before PATCH[2] since PATCH[1] and PATCH[2]
point to same commit.

Thanks,
Gavin