Re: [PATCH v5 07/17] mm: pgtable: introduce pagetable_dtor()

On Wed, Jan 08, 2025 at 02:57:23PM +0800, Qi Zheng wrote:
> The pagetable_p*_dtor() are exactly the same except for the handling of
> ptlock. If we make ptlock_free() handle the case where ptdesc->ptl is
> NULL and remove VM_BUG_ON_PAGE() from pmd_ptlock_free(), we can unify
> pagetable_p*_dtor() into one function. Let's introduce pagetable_dtor()
> to do this.
> 
> Later, pagetable_dtor() will be moved to tlb_remove_ptdesc(), so that
> ptlock and page table pages can be freed together (regardless of whether
> RCU is used). This prevents the use-after-free problem where the ptlock
> is freed immediately but the page table pages is freed later via RCU.
> 
> Signed-off-by: Qi Zheng <[email protected]>
> Originally-by: Peter Zijlstra (Intel) <[email protected]>
> Reviewed-by: Kevin Brodsky <[email protected]>
> ---
...
>  arch/s390/include/asm/pgalloc.h            |  6 +--
>  arch/s390/include/asm/tlb.h                |  6 +--
>  arch/s390/mm/pgalloc.c                     |  2 +-
...
>  include/asm-generic/pgalloc.h              |  8 ++--
>  include/linux/mm.h                         | 52 ++++------------------
>  mm/memory.c                                |  3 +-
>  28 files changed, 62 insertions(+), 95 deletions(-)
...
For s390:

Acked-by: Alexander Gordeev <[email protected]>

Thanks!