Re: [PATCH] s390/mm: Add missing ctor/dtor on page table upgrade

[Qi Zheng]

On 2025/1/24 00:03, Alexander Gordeev wrote:
> Commit 78966b550289 ("s390: pgtable: add statistics for PUD and P4D
> level page table") misses the call to pagetable_p4d_ctor() against
> a newly allocated P4D table in crst_table_upgrade();
>
> Commit 68c601de75d8 ("mm: introduce ctor/dtor at PGD level") misses
> the call to pagetable_pgd_ctor() against a newly allocated PGD and
> the call to pagetable_dtor() against a newly allocated P4D that is
> about to be freed on crst_table_upgrade() PGD upgrade fail path.
>
> The missed constructors and destructor break (at least) the page
> table accounting when a process memory space is upgraded.
>
> Reported-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/20250122074954.8685-A-hca@xxxxxxxxxxxxx/
> Suggested-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
> Fixes: 78966b550289 ("s390: pgtable: add statistics for PUD and P4D level page table")
> Fixes: 68c601de75d8 ("mm: introduce ctor/dtor at PGD level")
> Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
> ---
> The patch is against:
>
>    git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git	next-20250123
>    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm			mm-stable
> ---
>   arch/s390/mm/pgalloc.c | 3 +++
>   1 file changed, 3 insertions(+)

Acked-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>

Thanks!