Re: [PATCH mm-hotfixes v2 4/4] arm64: remove redundant concurrent ptdump UAF mitigation

[Will Deacon]

On Sun, Jul 12, 2026 at 11:42:27AM +0100, Lorenzo Stoakes wrote:
> This partially reverts commit fa93b45fd397 ("arm64: Enable vmalloc-huge
> with ptdump"), retaining vmalloc-huge support but eliminating the now
> redundant mitigation against a race between huge vmap page table freeing
> and ptdump, as this issue has now been fixed at core.
> 
> We also simultaneously remove the arm64 if-deffery when acquiring the mmap
> read lock upon vmap huge page table promotion as it is no longer required.
> 
> Note that this patch relies on the preceding vmalloc patch, and should not
> be backported alone.
> 
> Fixes: fa93b45fd397 ("arm64: Enable vmalloc-huge with ptdump")
> Cc: stable@xxxxxxxxxxxxxxx
> Reviewed-by: Dev Jain <dev.jain@xxxxxxx>
> Acked-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
> Signed-off-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/ptdump.h |  2 --
>  arch/arm64/mm/mmu.c             | 43 ++++-------------------------------------
>  arch/arm64/mm/ptdump.c          | 11 ++---------
>  mm/vmalloc.c                    | 15 +++-----------
>  4 files changed, 9 insertions(+), 62 deletions(-)

Acked-by: Will Deacon <will@xxxxxxxxxx>

Will