5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dev Jain dev.jain@arm.com
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 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@vger.kernel.org Reported-by: Ryan Roberts ryan.roberts@arm.com Acked-by: David Hildenbrand david@redhat.com Signed-off-by: Dev Jain dev.jain@arm.com Reviewed-by: Catalin Marinas catalin.marinas@arm.com Reviewed-by: Anshuman Khandual anshuman.khandual@arm.com 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/mm/mmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1041,7 +1041,8 @@ int pud_free_pmd_page(pud_t *pudp, unsig next = addr; end = addr + PUD_SIZE; do { - pmd_free_pte_page(pmdp, next); + if (pmd_present(READ_ONCE(*pmdp))) + pmd_free_pte_page(pmdp, next); } while (pmdp++, next += PMD_SIZE, next != end);
pud_clear(pudp);