[PATCH v3] arm64: Restrict pagetable teardown to avoid false warning

[Catalin Marinas]

On Tue, May 27, 2025 at 01:56:33PM +0530, Dev Jain wrote:
> Commit 9c006972c3fe removes the pxd_present() checks because the caller
> checks pxd_present(). But, in case of vmap_try_huge_pud(), the caller only
> checks pud_present(); pud_free_pmd_page() recurses on each pmd through
> pmd_free_pte_page(), wherein the pmd may be none. Thus it is possible to
> hit a warning in the latter, since pmd_none => !pmd_table(). Thus, add
> a pmd_present() check in pud_free_pmd_page().
> 
> This problem was found by code inspection.
> 
> Fixes: 9c006972c3fe (arm64: mmu: drop pXd_present() checks from pXd_free_pYd_table())
> Cc: <stable at vger.kernel.org>

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>