Re: [PATCH 5.15.y] arm64: Restrict pagetable teardown to avoid false warning

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 650768c512faba8070bf4cfbb28c95eb5cd203f3

Status in newer kernel trees:
6.15.y | Present (different SHA1: 1d03bbcb2b98)
6.12.y | Present (different SHA1: 47f34289d100)
6.6.y | Present (different SHA1: 6562806f3200)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  650768c512fab ! 1:  fe24ec1815e3d arm64: Restrict pagetable teardown to avoid false warning
    @@ Metadata
      ## Commit message ##
         arm64: Restrict pagetable teardown to avoid false warning
     
    +    [Commit 650768c512faba8070bf4cfbb28c95eb5cd203f3 upstream]
    +
         Commit 9c006972c3fe ("arm64: mmu: drop pXd_present() checks from
         pXd_free_pYd_table()") removes the pxd_present() checks because the
         caller checks pxd_present(). But, in case of vmap_try_huge_pud(), the
    @@ Commit message
         Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
         Link: https://lore.kernel.org/r/20250527082633.61073-1-dev.jain@arm.com
         Signed-off-by: Will Deacon <will@kernel.org>
    +    (cherry picked from commit 650768c512faba8070bf4cfbb28c95eb5cd203f3)
    +    (use READ_ONCE since pmdp_get() is not defined)
     
      ## arch/arm64/mm/mmu.c ##
     @@ arch/arm64/mm/mmu.c: int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
    @@ arch/arm64/mm/mmu.c: int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
      	end = addr + PUD_SIZE;
      	do {
     -		pmd_free_pte_page(pmdp, next);
    -+		if (pmd_present(pmdp_get(pmdp)))
    ++		if (pmd_present(READ_ONCE(*pmdp)))
     +			pmd_free_pte_page(pmdp, next);
      	} while (pmdp++, next += PMD_SIZE, next != end);
      
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |