Re: [PATCH] mm: kfence: fix PG_slab and memcg_data clearing

[Muchun Song]

> On Mar 21, 2023, at 05:29, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> On Mon, 20 Mar 2023 11:00:59 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote:
> 
>> It does not reset PG_slab and memcg_data when KFENCE fails to initialize
>> kfence pool at runtime. It is reporting a "Bad page state" message when
>> kfence pool is freed to buddy. The checking of whether it is a compound
>> head page seems unnecessary sicne we already guarantee this when allocating
>> kfence pool, removing the check to simplify the code.
>> 
>> Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
>> Fixes: 8f0b36497303 ("mm: kfence: fix objcgs vector allocation")
>> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> 
> I'm not sure how the -stable maintainers are to handle two Fixes: tags.
> Can we narrow it down to one please?  I assume 8f0b36497303 triggered
> the bad_page() warning?
> 

Actually, 0ce20dd84089 triggered the PG_slab warning and 8f0b36497303
triggered the "page still charged to cgroup" warning. This patch fixes
both warnings. Moreover, 8f0b36497303 fixes 0ce20dd84089 as well. So I think
we can narrow it down to 0ce20dd84089.

Thanks.